Here you go:
Code:
mount -o loop -t iso9660 /path/to/file.iso /mount/point
Once you do this you will be able to access the /mount/point directory (or whatever other directory you mounted the iso on) as if it were another directory with files on your system.
EDIT: to mount the iso each time you boot:
In your /etc/fstab file add the following line:
Code:
/path/to/file.iso /mount/point iso9660 ro,loop=/dev/loop# 0 0
The # in /dev/loop# is a number from 0 to 7. That's how many loop devices are made by default so you can mount up to 8 iso images. If you want more, create more loop devices.