Ok, thanks for the confirmation on technique.
As for the torque, the Shimano specs ("Front Drive System" info sheet) that came with the crankset say 35-50 Nm (435-608 in-lbs). When I have used a torque wrench, I've aimed for the lower value, which seems to be about as far as is convenient to go anyway. Six hundred in-lbs is quite a torque. I don't think I'd want to try to go that high without a more secure arrangement for for the tool in the adjustable cup.