Do you modify classes?

[Flexor the Mighty!]

I'll alter classes but not to the degree of letting that encroach on the domain of another class. If they want a wizard who can open locks as only a rogue can..well they can take levels of rogue. But altering requirements for a prestige class is fine, or stuff like that.

 

[MonsterMash]

Add me to the setting specific changes group, not normally for individual characters.

 

[D.Shaffer]

As a default? No.
On a case by case basis, yes, but they better have a good backstory attached to it. Something small like a skill change would have a higher chance to get approved.