Stephen, fyi i got mythtv working with the virgin stb via infrared control...All the channels etc are in place, guide etc working....
It was straightforward enough once I got to the point where I understood how MythTV worked but to get to that point i had to make a few mishaps along the way...such as using the channel search facilty in myth setup....how i expected that to work I will never know, given that i had the stb connecting simply through composite in to my pvr card....
I used the xml feed (http://homepage.ntlworld.com/justin.hornsby2/virgin.xml
) created by Justin Hornsby, modified one of his perl scripts to auotmatically create the source channel files for Myth, ran mythfilldatabase to get the guide for the source channels and then added a new script to assign the channel numbers using the same xml file. So the xml file proved to be a good find and my thanks goto Justin for that.
I also used Venom986 process and script for setting up the channel changing via infrared control ( http://forum.linuxmce.org/index.php?topic=4302.0
)...may not be relevant to you if you are able to do it via serial. But it works a treat and means i can actually make use of all these MCE blaster I have lying around.
I will put the steps i went through down in a Wiki, for the benefit of others who may come at this as blind as I did, hopefully have that done for tomorrow evening.