How to install persistent T1 fonts on laserjet?

I have a HPLJ2420. It has a Compact Flash slot and I put a 256 MB card in. I would like to put PS fonts on it so they are permanently available.

I can't find any utility that lets me do that (HP's Web JetAdmin purports to, but I can't get that running properly; and it's a huge hog of a program anyway.)

After initializing the card, the printer can display a file directory. It shows 3 directories:

0:\PermStore

0:\PostScript

0:\PJL

I'm unable to find any references, but I assume that the printer reads and executes/installs whatever it finds there on booting.

It has a format that cannot be read in a card reader connected to a PC (at least when I tried it), so I can't prep it  that way. But I think I can use PJL commands to put files on the card in the printer.

So what file format should a Type 1 font be to be recognised and installed?

I'd guess something like PFA, maybe with some magic added.

Has anyone any suggestions or already have solved this?