Heating Tempering News Today

I am making a DTI holder from drawings by Stefan Gotteswinter. He specifies that some of the parts should be hardened and, presumably, tempered. These bits (not finished yet) are made from 01 Tool Steel, I am pretty confident I can harden them by heating with a torch then quenching in oil but not so sure how to go about tempering - or if that is even necessary? I understand the principle of reheating and watching for colour change but that usually seems to be done on larger parts where the heat...