Isomaster is an excellent free program for manipulating iso files in Linux. Many distros include it as standard kit.
You can build it on Centos 6 if you have the build tools and kernel set up properly, so fix the kernels if necessary.
Download Isomaster into home directory.
Move to /tmp
$ cd /tmp
$ sudo su
# tar xjf /home/<user_name>/isomaster-1.3.9.tar.bz2
# cd /isomaster-1.3.9
# make install
# cd out of build directory
# rm -rf /tmp/isomaster-1.3.9 delete build files
# exit to unprivileged user
Run it with
Fluxbox users can put in their /home/<user_name>/.fluxbox/keys file
Mod1 i : ExecCommand isomaster
To run it with 'Alt i'
See Fluxbox key bindings for more.