I actually did this in my old 944. It was mostly luck that it worked, but what the hell...
I had done a rear seat delete to add speakers in the seat wells, but then the first mini-me was conceived, so that went on hold (and actually never realized). My wife had a 4-door Toyota, but it decided to retire, so before we bought the Subaru, we had to make do with the 2+2. Our safety seat fit perfectly atop the trans axle hump, and it was secured by the existing seat belts attached to the hump (I might have had to move a male or female end... can't remember now... was 5 years ago). At any rate, it was legal and did the job. Yeah, it looked funny as hell, too, but it worked!
Hope that helps....
