You could probably still connect to the SD guide service with the special firmware if somebody uploaded it, but it would still violate the SD TOS to do so. Considering how, er, "unique" () the VRX firmware has proven to be thus far, it would not surprise me if it doesn't even implement the SD protocol correctly and has some distinct behaviour that would allow SD to identify VRX connections from those of other devices. If that's the case, SD could very well block the VRX from downloading the guide, even if you have the special firmware.
Even if you manage to circumvent the restrictions for the time being, you're leaving a financial paper trail by paying for the guide that should allow SD to know who you are. If they find out that you're violating the SD license, they might terminate your guide service and could refuse to serve you as a customer in the future, even if you start using a licensed device. If SD took such a hard stance, you'd probably have to change your name and address to get access again. Considering the risks, I wouldn't advise anyone to continue accessing the service on the VRX. If this isn't enough of a deterrent, then at least consider the moral obligation you have to respect SD's terms. It's a non-profit organisation dedicated to provding an affordable TV guide, and you should respect its terms if you're going to use its service.