Several modder's over on discord are trying to solve this. If they find how to do this properly, I'll be happy to add it to Monkey.Could you make the main character lie on his back in the next issue and assign any of the buttons?
Laying on the floor is the easier issue. In the current games girls have no locomotion (i.e. they are pinned to their pose). It's already challenging to perform any type of insertions, so I can't imagine how this will work out. The suggestion I made there is for the dev to support male positions as part of the posing system.
-T-