Well you can have a third guitar somewhere near the middle. JP plays stereo live and uses a delay between the 2 sides as well as differant and some subtle modulations (chorus, additional delay, EQs..). A delay separating 2 speakers playing a mono track will make it wide, just don't abuse the lenght (keep it below 20ms).
In the studio, it's probably quad-tracked with minor changes between the takes (pick-ups, light equing).
edit: well Outlaw, you were faster than me ;P but I'd add... JP uses a MESA Mark V, it's badass.