its simple. my gp does the same thing. just slide the knob (the one that slides from L to R, located under the light switch) all the way to the right,, until it clicks, then slide it back. so every time you close the door, or just open and shut it for a second, just rememder "slide Right, click, slide left), and the lights shut off automatically and stay that way as long as you keep the door closed.

2002 GP GT 3.8 N/A, tined head/tail lights, brakelamp/LP lamp/taillamp toggle switch