DNS Changer Trojan on OS X 10.6.4

I have an intel mac running OS X 10.6.4 which has picked up a DNS Changer trojan that keeps changing his DNS entries to 85.255.*.* address and intermittently redirecting him to a webpage that emulates a "windows security alert"

Ive downloaded ClamXav which doesnt work as it wont update with latest virus definitions.

Ive also tried DNSchanger.com and run the tool from there but initially says dns changer found, but when you choose clean it says its not found. Ive not found a version of this tool newer than 2008 and dont think it works on 10.6.4

Anyone got any idea how I can rid the machine of it, preferably for free ?

ta

1st off, don't put in your master password to install anything from nefarious sites again.

Then you can try this.

If you got infected with a newer variant the removers probably won't work. If it comes to that you can restore from a backup or try a manual removal. It's probably an Internet plug-in causing the problem. You can poke around in two folders:

/Library/Internet Plug-Ins and
<User>/Library/Internet Plug-Ins

If the problem affects all users then look in the first folder; otherwise, I'd look in that particular user's plug-in folder.