Gimp on Mac: finding all your folders?

[Turnerea]

I use LR2+Gimp on my MacBook, and I tend to keep all my images on a hardrive I have hooked up to my airport. I can't seem to navigate to the hard drive through Gimp, so I'm always copying and pasting the files I want to my desktop so I can find them with Gimp. (I tried putting an alias pointing to the folder on my drive, but Gimp won't show this folder!)

So basically when I go to open a file in Gimp, the simple interface it gives doesn't allow you to navigate to the place where you'd see "Macintosh HD" and any mounted CDs, where my Airport Disc is also displayed (as a shared drive). Any tips would be great.... thanks!