This is so easy, the second time :-)!
You will need somewhere to mount the ISO. If you are expecting to do this more than once then create a specific ISO directory.
sudo mkdir -p /media/iso
Now you can mount the iso,
sudo mount -o loop /path/to/your.iso /media/iso
To access the iso image simply cd or access /media/iso which is now the root of your image.
When you are all done you can umount the image with
sudo umount /media/iso