[Roger]

Here is a screen shot of a Limit Switch test I had done. (I'm assuming you're using easyC for Vex.) Limit Switches are the same as Bumpers, just more sensitive and less durable, and the pretty easyC icon is different. The limit variable is an int. Change Digital Input number to suit, add PrintToScreen's to test the alternate conditions, and add SetMotor's to taste.

If I remember, there was some code that, if front bumper was hit, drive motors backwards and turn left 90 degrees, else let the driver drive the motors.

And, yes, check out the Vex PDF for the full explaination. I just get impatient reading it sometimes.