Bingo...
The rear blower motor is powered by the PK/W wire which should be fed from fuse #6 in the IP fuse panel (7.5A mini). That power is fed to the motor, and the switch controls the ground. The switch feeds back out to ground through the R/O wire which connects to the R/O wire on the back of the instrument panel HVAC switch assembly, specifically at pin #4. You could run it to ground, but it'll run all the time, except for when the key is off. (i.e. even if you turn the switch on the dash off, the rear fan would still run)
That should get the blower motor working.
There's also a feed for the rear air door actuator (which I always thought was just a mechanical link, but maybe not??). It might trigger something in the dash, or it might not... I don't have a clue. It's fed via the GY/Y wire from fuse 10 (7.5A mini) in the IP fuse box as well.
Now, as for the auxiliary power point, IP fuse panel #22 (20A) feeds the BR/PK wire, and grounds through the black wire in that same connector.
Does that help?