I’ve been using this script for years. It takes Type1 font files, runs them through the right conversion programs, and updates psfonts.map. If you’re using teTeX. Other distributions have different disk layouts.
The only problem with this approach is that every single time I upgrade Debian, it overwrites some of the files, so suddenly my displays look like on the right: Typeset with Futura metrics, but using a different font for display, so it looks all arty and stuff.
There’s surely a better way to do this, but, meh. The lesson to be learned here is: Never upgrade!