Thanks for all your help!
I did some experimenting myself, and here's the technique I came up with.
I wrote down all the little details that I noticed as a first timer. Since that's probably going to be the audience for this post I thought it would be helpful.
1. Do this while your front seats are removed. You'll really appreciate the space.
2. If you removed your rear bulkhead cover, put it back in place before reinstalling the rear seat. It's easier that way.
3. Tape some old towels over the sill of the rear entry door...there are nuts on the bottom of the seat that will try to scratch it as well as some fiberglass on the front of the seat.
* See my photo where previous maintainers have scratched this aircraft. Protect the whole sill, but make sure these parts are especially protected in a way that has as little thickness as possible.
4. With painter's tape (or some other gentle tape) tape the seats down in the folded forward position. That will make the seat easier to wrangle.
5. Slide the seat through the rear window in the orientation that it will be at in the plane (don't worry about getting it aligned in any particular way). Let the starboard side sit low in the fuselage and leave the port side high, up above the sill
6. Climb in to the plane and sit on the spar that's under the front seats, or on the center console if it is in place.
7. Extend the rear seat belts to their full length.
8. Un-tape one seat back to give yourself some room...thread the seat belts through the cutout in the seat pan in the orientation you need them (to avoid twists)
9. While sitting in the cockpit you can easily thread the bolt w/ washer through the seat, through the end of the seat belt, and through the bracket on the bottom of the seat and then install and tighten washer and nylock nut (no need to tape seat belts in place or do anything crazy to get the seat belt anchor bolts in)
10. Tape the seat back back in the down position to help keep it out of the way
11. Place the starboard front corner of the seat slightly ahead of proper position...above the spar and up against the fire extinguisher, below the vent and behind the seat belt reel for the front passenger seat.
* See photo below
12. Check that your towel is still in place on the door sill...this next step is where the scratches come from!!!
13. Rock the port side of the rear seat forward so that it drops/rocks into the plane with little to no effort...the seat will tip forward a little...note that the seat is still hung up on the sill a little further back.
14. Once the front part of the seat is inside the sill, and the rear seat is tipped forward slightly, slide the port side of the rear seat towards the back the plane. As it slides back you'll make enough room for the rest of the seat to fall into the fuselage with little to no effort (and no scratches).
***For me this was "the trick"...learning to slide the port side towards the front of the plane to slip the front part of the seat under the sill, then sliding the port side backwards to make room for the back of the seat to fall below the sill.
15. Once below the sill, it takes a bit of pressure (the seat pushing against the upholstery, mainly) to slide the seat into position.
16. To finish, put the rest of the bolts in, in accordance with the AMM.
These are the two places on the sill where the seat gets really close. The scratches are from previous annuals.
This is the spot where you want to put the front, starboard, side of the rear seat to create the space you need