Courtesy lighting
 

I've a Boxster S, 2001, 3.2l 6 speed manual. No door speakers and no door lights.
Is there a cost effective and, non damaging way, to install courtesy lights in the door panels without damaging the panels?

Not sure what color your interior is, but qualityporscheparts on eBay often sells complete door cards. You could get the lights and speakers.

Here is a tan one they have listed.

98 Boxster RWD Porsche 986 L Beige Vinyl Interior Front DOOR PANEL card 47,520 | eBay

okay, signed: Have the same question

I think (too long ago, when I was looking into that) the challenge was/is the wiring loom (same for retrofitting door speakers).
I might be wrong, but the necessary cables are not inside the door (or better the door wiring loom). If so, that would make stuff A LOT easier.