I dont see where having an "H" dro does anything for you. Can you explain how it would help you. There are only 2 things invloved the tool Radius(diameter) and length(height) both are covered by the tool table. To invoke the length you use G43 H(tool#) +leadin move and for Radius it is
G41/G42 D(tool#) + leadin move
Just a thought,
(;-)