If you love customizing your PSP, you might want to take a gander at NightStar3 and codestation's newly released ZeroVSH Patcher.
As the devs explain it, this plugin "allows users to customize their PSP to the fullest extent". It can load resources, fonts, gameboots, and modules without writing to flash, so there won't be any risk of running into issues (like bricking) associated with that process.
This initial release has been tested to work on M33, TN, PRO, ME, and GEN custom firmwares. It will also likely work on other custom firmwares derived from those mentioned, although this is untested. The ZeroVSH Patcher plugin currently supports the following file formats:
- Fonts - .pgf
- Bitmap Images - .bmp
- Resources - .rco
- Gameboots - .pmf
- Modules - .prx
- (more to come hopefully)