I think I found an answer on the programmer at least.
From https://github.com/synthetos/TinyG/wiki/Programming-TinyG-with-an-External-Programmer
Your garden variety AVR programmers will not work, as they only support the AVR ISP protocol and not the PDI programming protocol required by the Xmega.
And I found one on Amazon that claims to support PDI, Including the Xmega chip.
Guess I’ll order one of those, as it would be handy to have around at any rate.
