Cam,
I attempted this in my Outback and fried the module. Never bothered to fix it. Not exactly what caused the frying but I ran pos and neg wires from the dome light to the footwell of both pass and driver.
I gave it another go in the XT and ran wires from the ignition ring light. It actually worked this time as I pre-cut all the lengths of wires and put them in place before connecting to power source. However, the lights I used didn't stick properly and they were the 'cool white' which were too harsh for me.
Since then, I bought some 'warm white' LEDs and attempted to install them a few weekends ago. Unfortunately, the pos and neg wires touched and blew the module again
Did a bit more research this time and figured out exactly how to fix it. Went to the wreckers and bought a second hand module (brand new they're hundreds of dollars - second hand - $50!) Installed the new module and recalibrated the keys to work with it and BAM. Done!
The new LEDs are a bit yellowy than expected but better than the old ones!
Personally, I think it's a cool mod if done right but either unplug the module before starting or at least disconnect the battery
This also happened to me