well, there are obviously multiple guitar tracks going on, so it's not all an effect, but the Harmonic Pitch post amp is the way to go.
You might have to create a user scale to get the harmonisation completely right, but it's definitely doable. 
Put the PITCH effect in the X slot (not in A, B,C,or D). This will make the harmonies sound more like separate guitars.
And try Formant
Has anyone tried using something like Melodyne to harmonize? Copy and Paste, tweak for key, etc?
When working on song ideas, I've used it for backup vocal lines, and have used it to change the melody in vocals or guitar lines.
It doesn't sound as "big" as singing/playing a separate harmony part, but if you want rhythmically tight harmonies, making them with Melodyne ensures they are completely locked in with the melody.
+1 For Melodyne
No, not Melodyne. But, you CAN use the Kemper for two and three part live harmonies.
If the harmonies are relatively simple, (Classic Rock bands like Thin Lizzy, Allman Brothers, etc) they can be pretty simple to program. If the music has complicated chord and modal changes, you may need more than one harmony rig per song.
This... or an iDEvice
