No idea what rubyripper is, but I'm going to hazard a guess that it's a ruby script to rip a CD. So, based on that assumption, first thing I would check is the source of the script to find the spot where that error text is emitted. Most likely it's "cdrom drive #{somepath} does not exist..." where the text inside the #{} is the variable where it's looking for your drive.
For whatever reason, either the author of that script hard-coded the path to the cd drive to be /dev/cdrom, or you have an environment variable that says that's where it is. Check the output of "env" for the latter.
Basically, you need to figure out which device under /dev is actually your optical drive, and then figure out how to tell the script that, whether it's by rewriting a line in the ruby script, changing an env variable, or something completely different (hard to say without knowing all the details of the system you're on).
Edit: OK, so a quick google search and now I know what rubyripper is. I also know that the second paragraph down on this site - http://code.google.com/p/rubyripper/wiki/Manual - basically says the same thing I do. You need to set the device path value properly. I should have asked initially... does /dev/cdrom actually exist on your system?