Basics

Normally the camera should support the USB mass storage interface, so you don't have to do anything special.
If it's not the case, emerge libgphoto2 and set the gphoto2 USE flag to various packages like digikam. I am not sure you can browse the camera as in file system in KDE with this solution though; you have to use digikam or another application. In GNOME it may be different since GVFS seems to have support for gphoto2 (not sure this is the case for kioslaves).
You can specify the CAMERAS variable in /etcmake.conf if you don't want to build drivers for all manufacturers.

Digital camera