Loco001 released over at MaxConsole (yes i had to email the coder to get the true source of the news) a new release of his Menuedit Prog for the PSP:
The program now supports changing the Startup sound from your PSP. How it works? First of all you need to get a wave file which is around 3 seconds long, that wave file has to be PCM and 16 BIT. Then you start MFAudio select ur wave file as the input and as the output u set the filename and set the channels to 1 (mono) and the frequency to 44100 Hz (others may work too!-but i didnt test (lazyness)). Then click process and u get a new VAG File. Startup my PSPMenuEdit 0.2 and go to the 'Edit Coldboot Startup Sound' Box. Browse for the opening_plugin.rco there. Then if u like u can click extract to get the current sound from the file but thats not needed. So when u want to insert ur new VAG File just click the reinsert Button and load ur new vag file. the program does the rest for u. The original file is 100.880 byte so ur new file CANT BE BIGGER, is the program notices that tis bigger it exits, if it sees that its smaller it padds it and inserts the new padded file into the opening_plugin.rco. Then the header gets patched and all is done, u can test ur file with the firmwaerlauncher from MPH or just have the balls and flash it to ur new firmware with the newest PSPSet that Placasoft will release veryyyy soon .
I included a sound (holyshit.vag) as an examples - just try it, it sounds cool on my PSP.