Dunno the specific build you're talking about, but it's not that hard to do by the mid levels:
Soldier -> Devastating Attack (damage threshold 5 lower)
Scoundrel -> Dastardly Strike (flat-footed foe automatically suffers -1 condition penalty)
Soldier -> Melee Smash + Stunning Strike (+1 damage to melee attacks; any melee attack that moves a target down the condition track moves him one extra level down)
By 6th level you could have:
1/ Soldier 1 -- Martial Arts I, Weapon Focus (unarmed) -- Melee Smash
2/ Scoundrel 1 -- Point Blank Shot -- Dastardly Strike
3/ Soldier 2 -- Rapid Strike, Skill Training (deception)
4/ Soldier 3 -- Stunning Attack
5/ Soldier 4 -- Martial Arts II
6/ Soldier 5 -- Running Attack -- Devastating Attack (unarmed)
7/ Solider 6 -- Martial Arts III
...
Next, take Weapon Specialization (unarmed), and then go into Elite Trooper for Greater Devastating Attack and Greater Weapon Specialization (unarmed)
- - -
Alternately, Gunslinger:
1/ Scoundrel 1 -- Point Blank Shot, Precise Shot, Running Attack -- Dastardly Strike
2/ Scoundrel 2 -- Quick Draw
3/ Scoundrel 3 -- Skill Focus (deception) -- Sneak Attack +1d6
4/ Soldier 1 -- Proficiency (rifles) -- Devastating Attack (pistols)
5/ Scoundrel 4 -- Deadeye
6/ Scoundrel 5 -- Sniper -- Sneak Attack +2d6
7/ Soldier 2 -- Rapid Shot
8/ Gunslinger 1 -- Debilitating Shot
9/ Gunslinger 2 -- Careful Shot
10/ Gunslinger 3 -- Deceptive Shot
If you Aim, you deal extra damage. Or you can make a "ranged Feint" with 2 Swift actions and deal extra damage. Either attack hitting *will* move your target at least one condition level -- but they stack. If you Aim at and hit a flat-footed target, you *will* move him down at least two.
Cheers, -- N