The live cds have an image of a linux hd on them. They are often compressed, and '-o loop' won't work on the compressed ones. I doubt you'll be able to access it, and even if you could, it would be like trying to exchange files between two ordinary hd-based distros. You may be able to get away copying small stuff, but the bigger apps will be confused and not work, because RH and Slack put stuff in different places.
You will not find source, tgz, or rpm on the cd because all the software is already installed and including their pacakges would waste space