[DennisAN]

The old trick in the Miata world is to put the driveshaft in the tranny output, put the tranny in gear, and turn the output shaft to make the input shaft rotate.

This is more difficult in the Boxster because of the internal diff. If you spin just one output flange, the other one counter-rotates without spinning the tranny. A long bolt in one output flange to contact with the case prevents this from happening, so you have one hand to spin the other flange and a free hand to push on the transaxle.