Is there a Fantastico script for installing MODx?
At present, no, but MODx is not particularly difficult to install. For the most part, you just copy the MODx files to the server and run the MODx install script. Look here to see the MODx installation guide. Bluehost.com provides a SimpleScripts install for MODx that is very fast and reliable. It normally installs the most current stable version of MODx and will also upgrade your site.