If you want to install (truetype) fonts globally you do it like this (RedHat 8.0.94 Phoebe):
1. Copy the fonts into the folder "/usr/share/fonts"
2. Run the command "fc-cache /usr/share/fonts"
The fonts will then be available to all users. It works on my computer, at least
(By the way, Bitstream have made a few truetype fonts ("Vera") available for the public. They look very good with KDE ! )
Of course, copying the fonts to the "~/.fonts" directory is also a fast and easy alternative, but then you will have to repeat the procedure for each user. :?