Welcome to the forums, G4mer91, from what I've read on the internet it's definately possible on Vegas 2, and with the Xbox Live Vision camera or a PlayStation Eye.
What version of vegas do you have?
Vegas 1 didn't support the feature for the PS3, due to the Playstation EYE not being released at the time, I don't know, if a patch has updated this though!
You should achieve it with the following:
1. Reset Character: Main Menu > My Character > Outfitting > Reset Appearance - Select, "Yes".
2. Character Customization: Gender - select, "Male" or, "Female", Appearance > Faces - Select the camera icon from the faces list( Make sure the Playstation Eye is plugged in). Select, "OK".
3. Everything from this point should be explained, it varies for each version of the game.