Hi! For our controllers, we use the left stick to control forward/backward, and right stick to control left/right movement. Is this something similar to what you want? A sample implementation of this could be something along the lines of
Code:
leftSpeed = y-x;
rightSpeed = y+x;
//y = Y axis of left joystick
//x = X axis of right joystick
If you have any other questions, please ask away!