I'm out at the moment, but:
If you go to cableforum and look the virginmedia section you'll see a thread that is about the iPad app.
I modified the script so that it makes it searches for your tivos and then creates the fake vm TiVo bonjour services, it works fine for me and others have it working fine. If my modifications don't work, earlier on in thread is the original script, but you'll have to enter ip addresses and tsn numbers manually into it.
Download and save the following pastebin to a folder as Zeroconf.py
http://pastebin.com/YYQsaF5z
Download and save to the same folder the following pastebin as vmtivo.py
http://pastebin.com/c2FSm3vR
Open a terminal and go to the folder and then type:
python vmtivo.py
You should see it find your tivos and then they should be be visible in the TiVo app. You'll see the real TiVo listed as well but it won't let you connect to it.
You need to keep the script running to keep the bonjour services being advertised.
Works fine on my MBP. If the script doesn't find the tivos, try running it again, the python zeroconf module seems flakey.
I'll knock up a cocoa app to do this which will not be flakey!