The Streamzap application natively supports 100's of apps, one of which is GBPVR. From what I remember they work on the basis - a user requests support for an app, tells them the application name and keyboard commands to map and they add it to their list. I have a streamzap and noticed the lack of full GBPVR support after I'd brought it specifically for this task and guessed whoever submitted the request didn't give them a full list of buttons to implement. I should really have a crack at getting them to increase support but instead I just switched to Girder. Its a programmable remote package with support for the Streamzap (and many other remotes) where you program it and train it, its a little fiddly to get your head round at first and its even harder to implement support for more than one application but I got it working for the two main tasks my lounge pc serves - GBPVR and WinDVD so I'm happy enough.
Basically send an email to Streamzap asking what info they need to add additional button support for GBPVR and they'll probably do it.
Intel i5-3450, 4096mb DDR3 Ram, ATI 5770 1GB, Windows 7 Pro
2 x Hauppauge Nova-T 500 (2 out of 4 of these I've bought works! Great QC Hauppauge!)
320GB WD SATA2 (For O/S / Music / Movies)
2 x 500GB SATA3 Seagates in a Windows Stripe (For Recordings)
Hauppauge MCE Remote Control
Samsung 46" LCD (Older model with Analogue Tuner - Hankering to upgrade)
New Zealand - Go Canterbury!