I got inverted tripod kinematics working, and in the right direction! 

*cue applause*

Eventually I gave up on figuring out how to make tripodkins invert on it's own, and just changed the source so it was always inverted.  

This of course still didn't work, because the initial values I had chosen for some of my parameters were so far off that they put tripodkins in the realm of mathematical impossibility.  But I digress..

Kinematics at least is all sorted now.  I'm hoping I can go back to normal tripodkins and it will invert now on it's own so no compiling for people.  We will see.

Homing works, and it's roughly dialed in.  I changed all the lines so they aren't all tied together in at least one point now.  :)

300mm/sec motion is flawless and smooth, my steppers are still turned down to just 1.2A, and it's hypnotic to watch...

It's also really dirty as it got sprayed with sawdust while in the garage, so no video until I clean it up.  Tomorrow.