If you want to grab a CVS snapshot of the forum here are the instructions. Please not this is for experienced users only and no guarantees about stability can be made of the CVS release, so caution is advised.
export CVSROOT=":pserver:anonymous(at)forum(dot)prohost(dot)org:/forum"
touch ~/.cvspass
cvs login
[press enter when prompted for password]
cvs -z4 checkout forum_install
this will get you the latest version
It is also possible to checkout separate files, for example by saying
cvs -z4 checkout forum_install/install.php
you would have checked out the latest version of the install script.