Hi Oyvind
The fastest way on the surface would be to block select where you would like to move the vocal strips to on the surface strip layout, then add the guitar channel to overwrite the duplicate left vocal channel.
Another way would be to use iLive Editor – in the strip mode on editor you can insert a channel between 2 strips, this is done by dragging a channel strip between 2 other strips. This will then move all the current strips on the rightside of where you inserting the channel to the right depending on how many channels you are inserting.
Hope you understand
Best regards
Sam A&H