The thread that Magicniner has pointed you at has all the information you need, but not necessarily in a very easily-used format. There is a lot of "noise" as well in that thread which doesn't help. I used that thread to get the base info I needed for my own tool length probing macros so I can sympathise if you are not a natural coder yourself. However, in that case (and bearing in mind that you would probably need to tweak anything you find for your own machine), one easy way forwards might be to look at Gerry's 2010 screenset which includes some very powerful XYZ probing tools. For $20, it might be a cost-effective alternative to semi-rolling your own.

Just a thought.