Transfer Fios Cable Card from Roamio to TiVoHD

I would like to yank the cable card from my Roamio Pro and stick it in an older TiVoHD that is currently hooked up to ethernet only (sans card). We transfer shows to the back room for viewing but would like to ditch the Fios STB and try a cable card (again). The current card in the Roamio is the specific M card that works properly so we can decrypt Cinemax, HBO, MGM and Sony Networks. The card is paired to the Roamio (and what a boondoggle that was back in August).



Is it possible to just pull and plug just to see if it works? Is it that simple?

Would I have to pair it to the TiVo HD?

Would I then have to pair it again to the Roamio once I have finished the experiment?



Any thoughts on how to do this? I'd like to see if the old TiVoHD still has what it takes before I order another card for it.