how the hell do you play wow with a gamepad?!? but to answer your question I got a logitec joystick that has a program to emulate keystrokes, ie when I move it to the left I can set it to be the same as pressing a. well actually no the joysticks can work for the mouse but I can asign all teh buttons to keys. anyway I'm sure you could get a gamepad working just have to use the program your pad came with and not an in-game setting.
fyi cheap gamepads don't come with programs. hell maybe they do now my damn $2 mouse came with a program lol