I've given it some thought, and I can't see anything wrong with posting this. If it is, delete it. But here goes:
Your Voom receiver can continue to fuinction as an OTA receiver only if you disconnect it from the satellite dish prior to calling and cancelling your service. The card never receives the kill signal, so it will allow you to continue getting OTA. There are some obvious drawbacks. You will have no PG info. You will not get any firmware updates. And if you ever plug it back into the dish your card will get zapped within a matter of hours.
So... there it is. Not exactly hacking (especially since this only benefits box owners aand not renters) but complicated and a bit of a pain. It at least gives them minimal value. I ran over a month and a half like this, so I don't think it would somehow stop.
-MP