There is a lengthy scene as the IMF team is in the Vatican to kidnap Davian. This clip shows the scene in the bathroom when the team grabs Davian.   Ethan is wearing a mask and is dressed as Davian. After they grab Davian, he has to speak into a device that lets Luther program Ethan’s voice to be that of Davian’s.

This scene shows both Ethan disguised as Davian as well as the actual Davian together.   In Mission: Impossible (I), the ending scene on the train has something similar, with Ethan portraying Jim Phelps and then Jim shows up.