Yes, you can, but you could with Dark Fire and Dusk Tiger too, and even could with the Gibson Digital Guitar. The six outs come from the piezo pickup, and are multiplexed down a standard cable that terminates in a FireWire interface that comes with the guitar (it's designed by Echo Electronics). The outputs show up in your computer as six separate inputs (one for each string). With Dark Fire and Dusk Tiger - and I presume this will be the case for Firebird X - you have two additional outputs: one for the magnetic pickups, and one for the piezo overall output (not individual strings, the same output used for the acoustic sounds).
I posted a review of the Digital Guitar when it first came out, and you can hear a bunch of
audio examples if you want to hear some of the things you can do with hex outs. My favorite application is running the bottom three strings through octave dividers, the top four through chorus, and the magnetic pickups through distortion. It's the setup I use with EV2, a two-piece band project with Brian Hardgroove (Public Enemy) on drums.
FYI Firebird X comes with Guitar Rig 4 (full edition, not LE) and Ableton Live 8 lite, and the patches I'll be designing for it once I have the interface here will be downloadable from the Gibson site.
I meant can it process each string individually with the on-board processors - so for example, could you load a smart harmony patch in the on-broad processors that shifts each string independently for a polyphonic harmonic shift that outputs from the standard guitar out? (Basically what the Variax does)