Can't be that simple.
 

I'm replacing the carpet in my 911. The rear seats appear to be held against the outsides with a slotted screw/bolt and slip onto a pin in the middle.

I can't get either side to move with a pretty big screwdriver--do I just need to lay into it, or is there some trick?

I had to take out those seat backs to install my bolt-in rollbar. If I recall the outside screws/bolts were not cooperative as you have found. I think used a big screw driver with a square shaft and an adjustable wrench on the shaft to turn it.

Good luck
Andrew

Yea, it's that simple.

But I had to file the end off of a wide chisel to make a super-screwdriver and then put vice grips on it to get enough torque to get mine loose.

Good luck.