The T handle rod has a threaded bottom end with a locknut on it. I've never had to adjust it but I imagine that's where you would do any adjustment.

I've had one of those in my RR. In my opinion its a PITA shifter. "race only" as far as I'm concerned. Not only is downshifting a PITA, but if its in a street car its a real nuisance getting into first at any stop. Drive any significant distance in stop-and-go traffic and in a half hour you'll have blisters on your fingers from pulling that T handle up!