I think what the OP is wanting is a fully automatic process so that when a toolchange is needed he just changes the tool presses a button and the tool will be moved to the touch plate, lowered and then the Z height is set accordingly, could be wrong though.
What I have for my mill due to me having collet holders is a height setter that is hooked into Mach, I bring the setter down onto a tool and press the buttons on screen and tell it what the tool number is, I then place the next tool in and repeat etc etc. That way I have all tools sitting ready to pop nto the spindle when needed. In the future I may build an auto tool changer which will make this even better
Heres a couple of pics of what I use.
Hood