To mount the ISO images, you'll need to have root access. Login as root or use sudo, and execute:
mount -t iso9660 -o loop,user image.iso /wheretomount
Drop ,user if you don't want users to access the iso files.
Hint: You can use cdemu to mount BIN images (It's in portage).
Hint 2: You can use mdf2iso to convert MDF/MDS files to ISO (It's in portage).
(is there a way to mount MDF/MDS without converting it to ISO?)
Hint 3: You can use nrg2iso to convert Nero's .nrg files to ISO (It's in portage). Or you can mount a .nrg file with:
mount -o loop,offset=307200 image.nrg /wheretomount