How to snap to a 3D object in reality?

[killwin98]

Sorry about my English, but I hope you could understand me. I'm looking for a software where I can use a scanned 3D model and then use a digitizer tool (for example digitizer tweezers). After applying some coordinates to the 3D model with that software I would like to reach to a certain specific coordinate in space, and the digitizer would snap to that point in the real-life 3D model (which is about 6x6x6 mm). Obviously one of the axes would have to be fixed with the digitizer on a rail or some sort.

Which software can I use to create something like this? Is there a guide for this kind of procedure?

Thank you in advance

Tom