I think you need the midi connection to edit or upload patches to the GT-8, but reading the specs you can use the firewire interface to hook it up - record and edit with whatever sequencing software you want to use.

I'm a POD user, so no direct experience.... based on what I'm reading, you can record over firewire. A firewire cable will cost you a couple of dollars if you don't already have one, so it's not much of a risk really...