Remove your plain jane overhead console and look for these.
Wires on plug A28
(1) Bluegreen = 12v+
(2) White w Blk tracer 12v-
(3) Violet w Wht tracer = to Combo Meter
(4) Green = 12v+ (tail SW activated)
(5) Yellow = to Temp Sensor
(6) Gray= from Temp Sensor
OEM auto dim mirror uses (1) (2) of A28 so you have it made for the aftermarket one.
M3 Overhead Map light plug
(1) White = 12v+
(2) White w Blk tracer 12v-