you cant just change the skin on the main character to become a hooker, you would also need to change the whole player model, which is a little more difficult.
the nearest thing i can think of is the candy suxx player model mod which is here
or you could use the cheat: ISTILLLIKEDRESSINGUP which cycles through all of the generic player models, utill you find the one you want (in your case the hooker). this is a lot easier than changing player models and modding bits of the game.
you would probably have been better posting in the mod forums though as this is more of a modification question. any way i hope this helps and by the way, the movie looks great.