This is what I know.
1) Buy a tool height touch off probe. Here is one but there are many.
http://www.cadcamcadcam.com/index.asp?PageAction=VIEWPROD&ProdID=10Issue is you need the room on the table to use the probe. A lot of times I am space constrained.
2) Buy a tool holder system like this Tormach.
http://www.littlemachineshop.com/products/product_view.php?ProductID=2441&category=209730719You will need a height check and indicator to find the offsets.
3) Go big and buy an automatic tool changer.
http://www.littlemachineshop.com/products/product_view.php?ProductID=2937Fits an mini mill don't know if it fits your system. I think you still need to buy the Tormach holders so throw in another $500 or so.
Otherwise feed the monkey.
Dan