The best way to convert a Catia v4 model to dmis is a product called CATCMM. CATCMM runs inside native Catia and creates inspection 3d point measurements, hole meas, clearance moves, probe changes, etc.
The data is automatically converted in dmis format ready to load into any dmis driven cmm.

My name is Larry Kuehn, I run an inspection service and specialize in inspecting Contoured Aerospace parts.
I use CATCMM to program 3 different types of DCC CMM's
For info on CATCMM, call CMM Products @ 714 545-4568 Ask for Perry