but I also need to get at them in plain tex.
It is the same story. Once you have the tfm files installed, you do
stuff like
\font\somename = tfmfilename
{\somename this is in some font.}
I don't think it will be trivial to create all the support files (tfm,
map, fd, ...). I am not sure if they already exist on CTAN, either.
Good luck,
Karl