[3.5] Can't find class for conman concept

[rooster]

There's a class in the PHB called the Rogue. I'd probably go with that.

But it's easy to tweak things to fit the character you want:

Switch the beguiler or telepath casting stat to charisma. Done.

Or

Trade the bard's music for wizard-rate feat progression, drawn from pool of skill-based feats. Done.
(Or just use oratory. Fixating and motivating people with your words is exactly what I'd think you'd want to do.)

Or

Trade the rogue's sneak attack for a bluff-based version of the bard's fascinate/suggestion.

Or

Use spellthief or marshal. I think they have appropriate skill lists. They certainly have charisma synergy.

Or

Write up a charismatic swashbuckler based on the rogue class:
Pull out all the trap abilities and UMD. Drop skills to 4+Int, slow sneak attack to 6d6 at level 20, bump HD up to d8, raise Will and BA to full progressions, add some swift- and immediate-action sleight-of-hand, disarm, fear, parry and feinting abilities and advance them with levels. You should be left with a decent framework for a fitting melee class.

...Rogue/Warlock's okay, but it'll be worse at the "conman" thing (assuming more than a 1-level Warlock dip) and will have less use for charisma than straight rogue.

Daggerspell Mage is nice skill-wise, but it's really squishy for a knife fighter.

Unseen Seer dodges the DM's "stand in the front line with your low ac, weak fortitude and d4 hd" dilemma. Tougher skill requirements, but they're worth it.