I have a smallish sportscar with grippy cloth seats and a fixed steering wheel. I don't have too much trouble sliding in with my PV kilts, but the wool ones don't slide on the seats as easy. I just don't have room in there to lift my butt or do much adjusting.
I take a piece of stiff paper, like brown butcher's wrap etc, don't use newsprint!, and cut a piece about the size of the seat. Place it in the seat and sit in the car sideways, do your sweep and get everything nice, and then rotate to the front, paper and all. I developed this idea by accident, but it's been working OK.