I have power windows, and the illumination in those switches is also controlled by the dash lighting. I just hooked up the LEDs (with serial resistance) in parallell to the proper pins in that plug. No new wires into the door (which would have been a pain...).

Edit: So doing door handle LED should be easy if you have illuminated switches in the door already. IIRC you'd have to drill a small hole and secure the LED with glue (mine are hotglued - through-hole in the centre/door pockets, glue only for the speaker LEDs)
I used 5mm high intensity LEDs, but for the door handle I'd probably go with standard LEDs and 3mm size.

/Michael