The web site http://www.linuxpackages.net provides Slackware packages of many applications. They claim that they are eventually going to support all major distributions as a sort of one-stop shop, but they've been around for several years and have yet to do this. I didn't see mgetty anywhere on the site, but give it a shot in case I missed it. Of course, you can build from source code and if you want to, make a package out of it.
