Just figured I would share my experience since in most of the research it covers the tech pack cars ditching their awful Alpines for another unit. Well I think most non-tech pack owners want to ditch their POS Alpine for another unit as well...but the wiring is completely different.
I apologize ahead of time-I was under a time crunch tonight and didn't expect it to go as quickly as it did or I would've taken pictures. I am kicking myself because I know how helpful they are, but I think the below description with the photos in the other thread should really help.
Steps are completely the same, the "Evora Stereo Install" thread is super helpful as far as pulling the dash apart. I highly recommend you pull the knee pad off under the steering wheel..while not mandatory, it makes running wires (Sirius/XM, bluetooth mic, etc) much easier.
99% of aftermarket dual-DIN HUs now will come with their chassis able to accept most BMW/MERC/TOYOTA chassis brackets instead of the ghey metal sleeves a lot of other cars use.
The Evora tech pack cars and non tech pack cars come with the SAME mounting brackets. The difference is on the non tech pack cars they only use a single screw on each side to secure the bracket to the HU. Most dual-DINs need two screws on each side, which the bracket will support, and most HUs include in the packaging.
As noted in the install thread, the rear of the HU is attached to some rubber mounting in the back that requires a solid strong pull to get the HU out once you have unscrewed the 4 black screws on the face. Just be weary as it is easy to yank your faceplate off the HU, despite it not technically being removable
The single DIN units also have that plastic shelf on the bottom-once you have removed all the trim, you can take it out. You can do it two ways-it is attached with GM-style interior trim fasteners (the black plastic pieces in the rear of the cubby) and if you have the proper removal tool you can pop them out. Otherwise a good yank will pop them both out easily. That is all it is secured with. The plastic fasteners attach to two L-shaped metal brackets that are attached behind the dashboard. I'm sure they could be removed from behind the dash or by removing the foam and a significant portion of the dash, but it wasn't worth it to me. Since it is pot metal, I just bent them straight and out of the way. You could easily bend them back as needed, but remember that it is pot metal and a few too many bends could result in them snapping.
After that just check all of the wiring (will be different for each case) you need and run accessories as appropriate. There is a decent amount of room behind the unit so if you have an XM box, Alpine powerpack etc you should be fine.
Someone alluded to it in the other thread, and I pulled the manual off of the Alpine website for the CDE-102 as well as checked the diagram on the top of the HU...none were 100% correct...so here is the wiring:
orange/purple=power antenna lead/boosted antenna lead
blue/white=remote turn on lead (this was included in the harness loom despite not having a factory amp..so I assume this is an artifact from the tech pack cars, and useful if you later add an amp in the rear, though you'll have to go digging for it)
white/black=front Left neg
white=front left pos
gray/black=front right neg
gray=front right pos
There was also an additional black/white wire that was not labelled on any of the diagrams/didn't make any sense...I didn't wire it up to my new HU and I have no issues.
So far it seems as if there is no conversion harness, so I just cut the wires. For me it isn't a big deal. The harness is short though so make sure if you do cut it, you cut it very close to the end.
Another quick note-if you need a solid ground for small amounts of current or for the back up camera/parking brake/DVD player override-use the 7mm hex bolt that is right next to the fuse box in the passengers side footwell...it's about 5" off the floorboard.
Once you have all of the looms wired up fasten the brackets to the side of the HU, slide it back in making sure all the wires clear the back, and fasten everything back up.
Quick note-if you have to slide the HU back out, it may cant upwards and get hung up on the bottom, at which point you'll have to use a long skinny flathead or something to lift up the bottom and shimmy it out.
All in all, it took me about 2 hours to pull the old one out and reinstall the new one. I have a bit of experience doing car audio stuff....but I think if you have a teeny bit of knowhow, you could accomplish it in 4 hours or less. No special tools were really needed.