1) use the ctf manager v2.0 to extract your ctf into flash0 contents. once you get that, open the EXTRACTED folder. go into vsh->resource. you'll see the opening_plugin.rco. CUT and paste that opening_plugin onto your desktop. if there's ANY gameboot in that folder, DELETE it since that's what you want to change.
2) next, go into vsh->module. IF there's an opening_plugin.prx, CUT and paste that too onto your desktop. this means you have removed 2 or 3 files from EXTRACTED folder.
now comes the editing part.
3) use RCOeditor and change the value of the opening_plugin.rco that needed to be changed. remember to click change or else the value will remain the unchanged.
Look at my first post on how to change the value
4) next up is HEXediting the opening_plugin.prx. the purpose of this is to make your gameboot run from your MS.
MAKE SURE THAT YOUR OPENING_PLUGIN.PRX IS DECRYPTED AND DECOMPRESSED.
Included below is the PRXcompressor. when you open the prx in your HEXeditor, you'll see top left of the text string as either 'PSP' or 'ELF'. if it's 'ELF', you're good to go. if not, decompress the prx.
5) right-click and find text string flash0:/vsh/resource/gameboot.pmf. place your cursor at the beginning of the
F in
flash 0 and type the following text string:
ms0:/PSP/SYSTEM/BOOT/.If done right the T in BOOT should finish before the backslash right before gameboot.pmf. what you'll end up with is
ms0:/PSP/SYSTEM/BOOT/gameboot.pmf
save the new prx.
now go into your flash0 and replace the opening_plugin.prx (vsh->module) AND opening_plugin.rco(vsh->resource) with the new ones that you just edited. now place the gameboot you would like to use in a folder name BOOT and place the BOOT folder in
ms0:/PSP/SYSTEM. make sure it's named gameboot.pmf. now you will be running a gameboot from your MS.
that's done. next is the re-creation of the EXTRACTED ctf. what you will need is available
HERE.
re-create the contents of your EXTRACTED ctf (which is now missing opening_plugin.prx, opening_plugin.rco and possible gameboot too). those missing files will be read from your flash0 while the gameboot will be read from your MS.
in future, if you wanna change your gameboot, you can edit the rco and change your gameboot from your flash0 and MS without the hassle of extracting your ctf again. HOWEVER, if you change your ctf theme, the gameboot may not be there as the new ctf may contain both opening_plugin.prx and rco. which in this case, you'll have to extract them again.