Well, I give up. There exists, next to the CSS 2.0 and CSS 3.0 (but apparently removed from CSS 2.1 for lack of support) @font-face selector, only one alternative.
For IE there is WEPT, creating .eot files (but it has a lot of restrictions). I didn't get it to work for IE 6 or 7.
For NS there was such a thing as webfonts. You were able to create those files with two applications, both vanished from the net. They both created .pfr files.
Various testpages I found online didn't work either. Every now and then one worked in IE
or NS. I haven't seen Opera use custom fonts at all.
Thing is... there is a certain support for custom fonts. Don't ask me for details because they're very sketchy. But if you're looking for a project that will get you world fame and some money, start working on a filetype that is accepted by both IE and NS (and FireFox?). I'm guessing Opera would be willing to create an update for support of such a filetype). It should be possible, at least if one of the headers has a dynamic size. It's gonna give you a serious headache to actually figure out the structure of the filetypes (the NS webfont program can probably be found when you really search for it, I didn't feel like it).
Cause if you have to wait for support of @font-face of the mainstream browsers...