Recording audio through firewire in GarageBand, possible?

If I hook up my XLR mic to my Sony PD150, then hook the camera to my MacBook Pro through firewire, I can record in Quicktime fine. However when I try the same thing in Garageband it doesn't work (in Preferences, the only 2 options are "in-built mic" and "in-built line in"; in Quicktime I get a "DV Audio" option which is my firewire input).

Does Garageband just not support Firewire audio at all, or is it just my particular setup that is confusing it?

Using Garageband 3

any help greatly appreciated 🙂