Let users choose to play with either an xbox or ps3 controller

Hello,

So I've gotten my game to work with an xbox controller. The problem is the controls seem to be mapped slightly different on xbox and ps3. Is there any way to get users with a ps3 controller and those with an xbox controller playing my game? Or will I have to create two builds.

At worst it would be nice to be able to select which controller to use in my game menu, but Unity doesn't let you modify the input manager at runtime...