I'm not really a fan of your install but to help...

Try tapping into the RAP module for the moon roof if you have one. I think there's another module in the rear, don't remember what for...otherwise, run wires from the RAP module you'll use on your H/U. You can even install toggle switches using 12v-always on or run wires back to your box. Have heated seats?...they probably have one too.