Hey all I just got my '89 CE from Dave's Guitars and I just wanted to share this with you all. I know I was looking for a Diagram when I got my '88 to put it back original and was ecstatic when this '89 came in and was Original. The "Metal toggle" PRS used back then is an ALCO MTG 226PA switch. It can be found on eBay fairly easily.
The wiring diagram is quite cool as when the pickups are in the "middle" position only the inside coils are active in series. It's great for Rhythm work