Linux Mint Forums

avant should be in the software repositories, just search for it in Software Manager or Package Manager or in the terminal run "sudo apt-get install avant-window-navigator". If you every want to install a program the best place to check first is always either of the package managers, they have hundreds of great programs and everything can be automatically downloaded, installed and updated in only a few clicks.

Just out of curiosity do you know what the package managers and repos are?

Maybe http://forums.linuxmint.com/viewtopic.php?f=42&t=18938 might give you some pointers.