get yourself a copy of the tsx service manual, its well documented in there. I did it earlier this year while tracing the wiring in my euro r mirrors.
You will definately need to remove the wing mirror from the door, so that will involve taking the door card off to disconnect the wiring harness, and then accessing the screws from behind the plastic cap in the front corner, there are 3 nuts that need undone, be sure to support the wing mirror from the other side once you've removed the nuts.
Now you have the full wing mirror off the car you need to seperate the baseplate from the mirror casing, that it done by removing the 3 screws underneath. Once they are out the baseplate will seperate from the mirror casing, slide the baseplate out of the way and look for the 1 vital screw, its because of this 1 screw hidden by the baseplate that you need to remove otherwise the mirror adjustment motor will fail to come free from the housing! It's this one screw that makes the labour charge so high! If you didnt need to remove this screw you wouldnt have to remove the wing mirror of the car! Also there may be a screw clamping down the wiring harness down to the baseplate, you'll need to remove this to gain enough slack in the harness so you can feed the harness through to the mirror casing so you can move that out the way once it free.
Now you have seperated the mirror casing from the baseplate, the next step is to disassemble the mirror casing to get to the indicator unit.
Begin by carefully priseing the glass off the mirror mounting by levering it up from the bottom so it pops off its clips, then lift from the bottom till the glue seperates and you can unhook the glass from the top. Once the glass has been removed you'll need to remove the 3 or 4 screws holding the black plastic "hood" onto the mirror casing Once thats removed you will see a few more screws holding the motor unit into the case of the mirror.
Once the final screws are out, everything will be loose and the motor will slide out along with the indicator unit.
Move the motor out the way and unplug the indicator unit by the small 2 wire plug at the rear. Plug the new one in and reassemble. It's pretty straight forward, just be extra carefull when you apply pressure to the glass to get it to pop back onto the holder as i broke the adjustment for the left right alighment on my mirrors, doh!
Sorry thats the only pics i've got, it was from when i was tracing back wires for my folding mirror swap. Hope some of that help anyway.
