You can also get Guitar Pro to change the channels on your VH4 via MIDI, so you can play and have the channels change at the correct point in the song :)
How? :)
Come on Oli, give a nice long explanation, I want to hear too.
Well, if you take a look through a small tutorial i made on it a while back:
http://oli.doom-metal.com/midipipe/. If you're not using a Mac, then you'll have to grab the MIXI-OX utility that Muttley posted. Basically, what we do is: Create an additional track in GP, to which you program in when you want the channel/patch changes to occur, and what the patch will change to. By putting the correct settings into GP, it will output that data through the MIDI interface, however.... GP only transmits Note changes, and almost all MIDI capable units use either CC (control change) or PC (program change) messages. That's where that other utility comes in, to perform a transformation, so that even though GP outputs the note message, what comes out of the interface is the CC or PC message.
It sounds more complicated than it is really! I've put up a sample file
here, so you can see what information has been written into the 'amp control' track. You'll see values for 2, 1 and 5 in there, and these correspond to the patches in my rig:
1 = Rhythm Distortion
2 = Clean w/chorus
5 = Lead
I'm not sure what the MIDI setup is with the VH4, but it shouldn't be anything too complicated (or too dissimilar to what i explain on the tutorial page).
It may take you a little bit of time to get it working, but once it is, it's very easy to continue (each new GP tab you want to play along to just needs that extra track, and the info for when to change).
If you get stuck, give us a shout, and i'll try and help :)
Oli