Hi Martin
This topic would be better asked in the TechNet forums that handle IT Administration questions. If it can be done, then you'd need a group policy of some sort...
I can move your question to TechNet, but it would help to know which version of Word is involved, first, so that I can put it in the correct forum there.
Other than that, the only possibility would be to disable the built-in command and substitute a UI of your own making.
Cindy Meister, VSTO/Word MVP