Shiva said:
Actually, upon re-reading the rules, I think you get an AoO regardless.
Moving out of a threatened square and performing a distracting act provoke AoO's, in these instances, from those that threaten you. This is explicit.
Starting a grapple provokes an AoO. Again, this is explicit.
Typically you don't get an AoO unless you threaten the square. But virtually all rules in DnD have exceptions and these are usually spelled out. Like Step 1 which says "You provoke an AoO". It is the very use of the phrase "provoke an AoO" that indicates to me that the character gets an attack, as provoking an AoO only occurs if an attack can actually be made. ie if an attack cannot be made, there is no provoking.
Now that's just not true. Sunder, tripping or disarming someone and these things are another example. So someone with 10 fot reach or more doing one of the above listed things (or a grapple attempt for that matter) against you (or any creature with only 5-foot-reach) don't provoke an attack of opportunity from you, since you don't threaten them in the first place.
form the SRD:
An enemy that takes certain actions while in a threatened square provokes an attack of opportunity from you.
[...]
Some actions, when performed in a threatened square, provoke attacks of opportunity as you divert your attention from the battle.
Now all those listed above fall into that category - just as starting a grapple (without improved grab). All say in its first step "You provoke an attack of opportunity from the defender/target", for trip it says "Make a melee touch attack. This as normal provokes an attack of opportunity fromthe defender"
All those still have to fulfill the required circumstances for an attack of opportunity. One of them beeing threatened by him!
Now you also mixed up the order I think. A normal character provokes more than one attack of opportunity in the process of starting a grapple: First, from the defender for making the touch attack, then when the grapple started successfully, by moving into his space. This provokes attacks of opportunity from everyone threatening the square(s) he leaves in the process. Now the defender does't get that attack of opportunity since he's already grappled at that point and therefore can't make AoOs (it's also explicitly mentioned in the description of the grapple).
Now the problem is that anyone with the improved grab ability pulls the opponent into his space, so the mone that moves is you (without provoking AoOs as explicitely stated).
So: No still no attack of opportunity against someone with reach trying to grapple you from outside your threatened area

I also know that you might want to allow this, if you think it's not unbalancing or too powerful for a single feat, but that would be a house rule and this is still a rules forum...