On my '06 TJ there's one spot I know of to pass through the firewall and that's on the driver side. There is a rubber plug off the the left a little behind the brake pedal. Just pull that out and cut an X in the tip of it with a box knife. And there u go. U have a path through the firewall.
As for the parking light i can't really help you there. My best bet is go to one of the lights and trace it back if u can. And also try and figure out what color wire the lights are using. Sorry.