Woohoo. I am done with a nasty project (and not laid off yet!) so would be pleased to answer any e-mails. My way of doing it was only one way, but I did learn a lot.
If I was starting over with the WRX I might try morrisdl's trick of moving the connector to recess the sled. That was *really* slick. In the WRX (if it would fit), it might mean that you could pop the bezel on at the last without the JB Weld lock nut maneuver I used. You'll have to cut the bezel in any event; the OE opening is just too small.
I sold the original 6-disk changer from the WRX for cheap to a friend with a new legacy wagon. She loves it. Popped right in.
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Jim
'Tis the exceptional fellow who lies awake at night thinking of his successes.