Are you running from cd or hd-install?

Could not claim the USB device.
This probably means you don't have permissions as user for the usb device. You could try launching gtkam as root; Open a konsole and type kdesu gtkam . Can you now use it?
If it asks for a password and you haven't set it (live-cd):
- open konsole
- type su
- type passwd
- type a password for root (twice)
- type ctrl-d to exit from root
- try kdesu gtkam again

Ah, found another howto: http://nift.freeshell.org/camedia.html Although this also requires a hd-install.

EDIT: Seems like you can klik Lphoto which sounds a bit easier: http://klik.berlios.de/