It's been a while since I installed it, so I took some pictures of how to go about getting to the harness.
Remove the scuff cover by pulling up.
Remove the kick panel by pulling out the plug first.
Remove this cover by pulling out.
Lower dash panel are held down two screws and clips. Remove these screws first and then pull the panel out. Make sure you don't lose any of the panel clips.
Once the panel is out, remove the metal plate held in by four 10-mm bolts.
This is the harness, tap onto the black/red wire.
Lastly, use the existing ground point in the kick panel area.
It seems like a lot of work, but it's pretty quick.