Depending on your bed geometry and build dimensions, it might be difficult to deploy and retract your automatic bed leveling zprobe using fixed points on your printer.

This part is a small tool that can be mounted on your frame and used during deployment and retraction of your probe. If you're building an automatic bed leveler following Johann's design, also take a look at the clamp that I designed here: http://www.thingiverse.com/thing:117981

Watch it in action here:
http://www.youtube.com/watch?v=IJor2vb2o-w

Repo:
https://github.com/jcdoll/kossel

1) Print.
2) Mount to your frame using an M3x8mm fastener and M3 hex nut.
3) Place the tool near one of your towers so that it can be reached but not impinge on your build area. Your usable build area is a circle but the addressable area is a triangle into which the circle is inset.
4) Update your firmware settings to deploy and retract nicely. See Marlin_main.cpp in my Marlin fork here for an example: https://github.com/jcdoll/Marlin