Constains a point to a selected object and bakes the cameras focus distance to that point.
Useful if you're rendering with Depth of Field and want to keep an object in focus throught a shot. Or if you want to do a rack focus you can animate a point helper to visually set your rack focus speed and then bake the focus out to that object.
To install just drag the download .MZP file into the 3dsmax interface. You should get an Install dialog.
This tool will install a macroscript that can be accessed from the Customize User Interface dialog within 3dsmax.