kbrandsma on Renntech posted the below info. I followed it and it worked great. I also posted a link to it but I believe you have to be a member to see it. Perhaps not.
from Krandsma.....
I recently decided to place some bright white LED's in both the driver's side and passenger's side footwells of my '98 Boxster. The lights are super thin and come with a 3M adhesive. I placed the driver's side LED strip on the vent tube that runs horizontally and the passenger's side LED strip accross the bottom of the footwell foam cover in the natural grove channel. The foam cover is held in place by 2 screws with large heads. Both sets of lights are wired together and are joined together on the passenger side above the foam cover (and now new LED light) and connect to two (2) wires, positive and negative, that run up the passenger's side "A Pillar" trim piece, then accross the top and connect to the center interior light. The positive is soldered into the "Y" shaped copper rocker inside the light switch and the negaitve is wire tapped into the center wire entering the switch.
It has the same off/on properities as the door lights with the added flair of manual on/off by turning on the center interior light. The center interior light and now footwells can be always on, always off and door and locking activated.
http://www.renntech.org/forums/topic/36995-footwell-lights/