How do I make a downloaded font ``persistent''?

%!PS-Adobe-2.0 ExitServer
%%BeginExitServer: 0
serverdict begin 0 exitserver
%%EndExitServer
% Test for existence of font, abort if present.
% This won't work on a printer with a hard disk!
/str 32 string def
/Eurostile dup FontDirectory exch known
{ str cvs print ( is already loaded!\n) print flush quit }
{ (loading font ) print str cvs print (\n) print flush }
ifelse
%% Font follows...

The part following ``%%EndExitServer'' is optional. If you use it, change Eurostile to the name of the font. The default PFA behavior is to use up additional VM for the new copy if another copy has already been downloaded.