One easy way to do it is to go to where they're stored on the PC. It should be at:
C:\Documents and Settings\All Users\Documents\RSView Enterprise\ME\HMI projects\<application name>\Images
At this location, all of the image files are stored as .bmp's and can be copied, etc.
If you copy one of the files and make changes, I would still import it into the project after the changes, because I have found the RSView Enterprise software to be very picky...