Automatic lock question

Here's the thing. My mom has a 1994 Lumina Euro, and she's tired of the doors automatically locking when she puts the car in reverse. I know with some cars and trucks, there's a way to disable this without cutting any wires, so is there a way to do it with this one? If so, how is it done? And if not, how would I go about getting rid of this annoying little "feature"?