I have created a batch file to make it easy to create fontsets for the PSP. It is basically a port of the included mkfontset linux shell script included with TTF2PGF. Just unzip this measly 343-byte file to your TTF2PGF folder.
To create a fontset, just double-click the mkfontset batch file. Enter the name of the folder for the converted files to go. Then you can enter the name of the font you want to convert. It must be in the TTF2PGF folder. You can then enter a second font. You can enter the same font twice. The files will be converted and put into the folder name you entered earlier. These files can then be copied to your PSP's fontmod folder. Restart your PSP, and, hey presto, new font installed!