I whipped this class up a couple of months back. Its similar to what you want. It is based upon the psion, and metapsionic feats. It has great versitility, however it has not been tested.
The Shapeshifter
HD: d8
Class Skills: Climb (Str), Concentration (Con), Craft (Int), Disguise (Cha), Heal (Wis), Jump (Str), Listen (Wis), Profession (Wis), Stabilize Self (Str), Swim (Str), and Wilderness Lore (Wis)
Skill Points per Level: 2 + Int modifier
BAB: as Cleric Saves: Will and Fort Good
Shifts known: As psion powers known (all shifts are in discipline)
SP per day: As psion in PsiHB w/o bonuses for ability score.
The shifter is proficient in all simple weapons and light and medium armor. If he wears any metallic armor, he may not use any shift powers.
Shifting: Shapeshifters manifest shifts in the same manner that psionicists manifest psionic powers. However, shapeshifters are not psionic, and have no access to psionic feats or attack and defense modes. To manifest a shift, the shapeshifter must have a wisdom score of at least 10 + the power level. Shapeshifters gain no bonus shifting points for high wisdom. At 20th level, the shapeshifter gains the type shapechanger and 60 foot darkvision in any appropriate form.
Shift Points: These are the shapeshifter’s daily allotment of points with which to manifest his powers. They come back after 8 hours of rest and 1 hour of meditation.
Talents: The shapeshifter can manifest a number of talents per day equal to his class level + 1 for free. Any beyond that cost the shapeshifter 1 shift point.
Metashifting Feats
Except Extend Shift, Persistent Shift, and Quicken Shift, these feats may only be applied to shifts in the shape chain. The maximum number of points that a shapeshifter can spend on a single shift is their class level.
Extend Shift
Doubles duration of a shift. Cost: 2 SP.
Master of Size
You may assume forms with sizes larger or smaller than those normally allowed by a shift at the cost of 2 SP/Size Category.
Persistent Shift
Prerequisite: Extend Shift
A persistent shift has a duration of 24 hours. Cost: +8 SP.
Power Shift
You may assume forms higher than your class level in HD at a cost of 1 SP/2 HD.
Quicken Shift
You may manifest any shift as a free action. Cost: +8 SP.
Self-referential Shift
You may use your own physical ability scores (before racial modifiers) as a base to which you apply the scores of whatever creature you are shifting into at a cost of 2 SP.
Template
Select a template that your character has encountered and has the appropriate shape shift for (see table below). You may add this template to any shape shift you manifest at the listed cost.
Template Required ShiftCost
Celestial (Good) Magical Beast 2
Fiendish (Evil) Magical Beast 2
Half-Celestial Outsider 4
Half-Dragon Dragon 4
Half-Fiend Outsider 4
Vampire Undead 4
Special: You may select this feat multiple times. Each time you select it, it grants access to a new template.
The celestial and fiendish templates grant damage reduction, all templates add the appropriate resistances and immunities. When an ability depends on HD use the shapeshifter’s class level.
Shifts
Note: all shifts have a range of self only, regardless of the original spell description.
All powers come from the psionics handbook unless noted otherwise.
Talents
Burst
Catfall
Elfsight
Float
Lesser Natural Armor
Talon
Verve
1st Level 1 SP
Biofeedback
Bite of the Wolf
Compression
Lesser Body Adjustment
Lesser Shape In this document. As alter self, but no significant physical changes.
Spider Climb As per PHB. Target of self only.
Vigor
2nd Level 3 SPs
Animal Affinity
Animal Shape In this document.
Body Adjustment
Body Equilibrium
Chameleon
Claws of the Bear
Darkvision
Expansion
Extra Shape In this document.
Humanoid and Monstrous Humanoid Shape In this document.
3rd Level 5 SPs
Beast, Dire, and Vermin Shape In this document.
Bite of the Tiger
Ectoplasmic Form
Improved Biofeedback
Rejuvenation
Water Breathing As per PHB, range of self only.
4th Level 7 SPs
Abberation and Magical Beast Shape In this document.
Immovability
Natural Armor
Ooze and Plant Shape In this document.
Psychofeedback
Stoneskin As per PHB. Range of self only.
Inanimate Object Shape In this document.
5th Level 9 SPs
Adapt Body
Dragon Shape In this document.
Emulate Gaze Attack In this document.
Legendary Animal Shape In this document.
6th Level 11SPs
Construct Shape In this document.
Emulate Breath Weapon In this document.
Improved Vigor
Suspend Life
Undead Shape In this document.
7th Level 13 SPs
Elemental and Outsider Shape In this document.
Fission
Oak Body
8th Level 15 SPs
Emulate Spell Resistance In this document.
Iron Body
Shadow Body
9th Level 17 SPs
Emulate Spell-like Ability In this document.
Shapechange In this document, revised.
True Metabolism
Shifts
Lesser Shape
Level/Cost: Shifter 1/1SP
As Alter Self except any organs created are vestigial (i.e. No flying, water breathing, or functional extra limbs.).
Animal Shape
Level/Cost: Shifter 2/3SPs
Duration: 10 min/lvl.
Manifestation Time: 1 action
This shift allows the shapeshifter to assume a single form of any Small or Medium size animal (not dire or legendary animals) of up to their class level in hit dice. This is in all other ways the same as Wild Shape. It ends immediately if you use any other shape shift.
Extra Shift
Level/Cost: Shifter 2/3 SPs
Duration: Instantaneous
Manifestation Time: Free action
This shift allows a shapeshifter that has already manifested a shape shift to switch to another form appropriate to the power he manifested (including any metashifting feats applied to the power). For example, a shapeshifter with animal shape manifested such that he can take large shapes may use this power to change shape into another animal of size Small to Medium with the appropriate number of hit dice. The duration of the original shift remains unchanged, so if the shapeshifter had 30 minutes left he would gain 30 minutes of his new form. If the same shapeshifter knew humanoid shape, he would not be able to assume a humanoid form with this shift, as he only had animal shape manifested.
Humanoid Shape
Level/Cost: Shifter 2/3SPs
As Animal Shape, except the shapeshifter can assume the form of a Small or Medium humanoid, monstrous humanoid, or giant shape.
Beast Shape
Level/Cost: Shifter 3/5 SPs
As Animal Shape, except the shapeshifter can assume the form of any Small or Medium beast, vermin, or dire animal.
Plant Shape
Level/Cost: Shifter 4/7 SPs
As Animal Shape except the shapeshifter can assume the form of any Small or Medium plant or ooze.
Aberration Shape
Level/Cost: Shifter 4/7 SPs
As Animal Shape except the shapeshifter can assume the form of any Small or Medium magical beast or aberration.
Inanimate Object Shape
Level/Cost: Shifter 4/7 SPs
As Animal Shape except the shapeshifter can assume the form of any Small or Medium object. They can still hear, and gain blindsight 10’. They get the hardness of the form they assume up to 1 pt per class level.
Legendary Animal Shape
Level/Cost: Shifter 5/9 SPs
As Animal Shape except the shapeshifter can assume the form of any Small or Medium legendary animal.
Dragon Shape
Level/Cost: Shifter 5/9 SPs
As Animal Shape except the shapeshifter can assume the form of any Small or Medium Dragon. Also, the limit is 1.5 times their class level in HD, rather than their class level.
Construct Shape
Level/Cost: Shifter 6/11 SPs
As Animal Shape except the shapeshifter can assume the form of any Small or Medium construct. If they assume a Animated Object form, then their hardness is limited to 1 pt per class level.
Undead Shape
Level/Cost: Shifter 6/11 SPs
As Animal Shape except the shapeshifter can assume the form of any Small or Medium undead.
Extraplanar Shape
Level/Cost: Shifter 7/13 SPs
As Animal Shape except the shapeshifter can assume the form of any Small or Medium elemental or outsider.
Emulate Gaze Attack
Level/Cost: Shifter 5/9 SPs
Manifestation time: 1 action
Duration: 1 round (see text)
When the shapeshifter is in a form possessing a gaze attack, the shifter may make a gaze attack & gains the gaze attack for 1 round. This gaze is identical to that possessed by the creature in all ways (ex. Range, effect, save DCs, etc.)
Emulate Breath Weapon
Level/Cost: Shifter 6/ 11 SPs
Manifestation time: 1 action
Duration: Instantaneous
The shapeshifter can use the breath weapon of their form. The effects are completely determined by form (Damage, save DCs, range etc.) The shapeshifter cannot manifest this power again until either their form could breathe again, or they have switched forms.
Emulate Spell Resistance
Level/Cost: Shifter 8/15 SPs
Manifestation time: 1 action
Duration: 1 minute per level
The shapeshifter gains the spell resistance of his form.
Shapechange
Level/Cost: Shifter 9/17 SPs
As Animal Shape, except there is no limit to the size or type of creature that can be assumed. (The HD limit still applies.)
Emulate Spell-Like Ability
Level/Cost: Shifter 9/17SPs
This shift allows the shapeshifter to use a spell like ability of 8th level or less of any form he has assumed. He may not use this power to use a spell-like ability more times than the given form could use it in a day.