I can't get to the nuts on the toilet seat in order to loosen them so I can change my broken toilet seat.

I just had the same problem.I can not believe that kohler would design such a flaw. I have four of these toilets in my house,and it would be ridiculously expensive to replace, especially for a seat. To fix it I went to OSH and got some 1/4-20 T nuts, went home cut the bolts off the seat (multi master dremel) with metal cutting blade. With a screw driver tapped the bolt and the small area around the bolt down into the toilet area. Now you have just a porcelain hole. Clean area with solvent (lacquer thinner),get some gel type super glue from hobby shop and put it on inside and top edge of the hole on the toilet. Put some glue around the shaft and under side of the T nut and slip it into the hole.Then put a SMALL bead of glue around where the T nut makes contact with toilet and let it dry aprox 1/2 hour. Now you have a permanent fix.To prevent a problem getting the bolt out in the future,put some anti seize (auto part store) on the threads of the new bolts. Hope this helps.
Good luck
Max