According to the package lists the repositories have:
So all you should need to do is either select it in the package manager and install or at the command line run:
sudo pisi it chromium-browser
If you've not installed any packages with the package manager before, you may need to go to the updates tab and let it scan the repositories before it will give you a full list of available packages.
P.S. Does anybody else think it's silly that Google have chromium, chrome & chrome OS? An obsession with the number 24 perhaps!