Perhaps this link might help. It seems to offer support for the mp620 as well.
http://sourceforge.net/projects/mp610linuxIf that does not provide enough support, then there is also a reasonably priced commercial solution called Turboprint. I have a Canon MP830 which was not not fully supported when I started using PCLinuxOS 2007 and I used Turboprint. The MP830 is supported in PCLinuxOS 2009, so it is perhaps also a matter of time. Here is the link to Turboprint:
http://www.turboprint.info/