First of all, change or remove all the male dialogue.
Second, you play the main game as a male or female and nothing changes, but what if it did? Use your feminine wiles to try and flirt your way past Frank, or maybe Patrick makes a drunken pass at you, perhaps you humiliate yourself on Ashley's behalf, or the most obvious example, give Amy your own panties.
There hasn't been a custom story that lets you be the biggest slut you could be and get what you want in exchange for your dignity. Let the female player get ahead by giving some head. Instead of pitting the characters against each other and manipulating them to complete various objectives, take the shortcuts that being a woman could possibly provide for you.
I don't know what else could come to mind but my point is, the player gender doesn't have much difference in the game itself and it'd be cool to see that happen.
