Let's face it, not all the tool you have on windows have exact Mac counterparts. CloneCD is one of them: Macs can sure copy CDs, but no Mac program can yet read or burn CCD images properly. There's a tool to convert them, though!
You may or may not know of a project called MacPorts. MacPorts aims to make UNIX (yeah, that thing Linux among others is based on) software work in your mac, which is pretty easy because Mac is also based on UNIX. This software is mostly command-line, meaning you run it from Terminal. As you may have guessed, so is our tool, ccd2iso.
After you've installed macports, you can install anything in its database by typing into Terminal "sudo port install <name>", without quotes. Sudo means it will run the command as 'root', or administrator, and it will ask you for the password.
To install MacPorts, you'll need to have XCode. This is Apple's developer stuff that enables macports to compile programs from source code fully automatic. Because of a lot of bloat it's a 3GB download, you can get it from Apple Developer Connection for free by making an account, or you may find it somewhere else.
After that, get macports from
http://www.macports.org. Remember, this might be useful for a lot of other tools, like browsers, IRC clients, text editors and many many more, so it's worth it. Follow all the instructions on the macports site for installing, and now you're a matter of seconds away from burning your CloneCD image.
Simply type "sudo port install ccd2iso" in the Terminal and enter your password. You won't see any stars or dots but it'll work. When it finishes, type "ccd2iso" to find out how to use it, simply though it's: "ccd2iso <path to .img file> <path to .iso file>". If you don't feel like typing out the full path, use 'cd' to get to the folder it's in first. You may want to look into a basic Terminal tutorial if you can't do this.
That should have finished by now, and you now have an ISO file that you can burn or mount with Toast, Disk Utility or basically anything!