Homebrew developer FreePlay dropped by QJ.NET PSP Development Forum and released an application called NewBTCNFedit. Basically, this tool helps users build a customized pspbtcnf.bin file for firmwares not supported by PSPBTEdit.

The coder also mentioned that this is highly useful for those who are on CFW 3.90 M33-2 because some programs like Go! Messenger runs on APP mode.

Aside from that, FreePlay also provided these additional information:

Valid modes are VSH, Game, Updater, POPS, and App, abbreviated as V, G, U, P, and A. To make a module load in one of these modes, just add it to the list after the module name. They can be in any order, upper/lower case, doesn't matter.