I'd say don't worry too much about a 'break-in' procedure for the transmission. I would assume that the machining of the gears and synchros is pretty solid so that any wear occurs within the first few miles of driving. I'd simply follow your clutch break in procedure and when you're done with the clutch break-in then simply change the transmission's gear oil.
"The 300ZX Turbo is a dance; it's a song; it's rolling, roaring automotive art. There is no color that doesn't suit it. There is no mood-lifting chemical substance it can't replace." - Automobile Magazine
