i'm going to work now, so i'll try with the firmware i've got when i get back.

i've successfully overwrote 2.6 with 2.6 with my method, which is a start, because i couldn't before. It's to do with the "loader".

Yes, u do need to change the params in the .sfo file to allow the PSP to even start thinking about running the Eboot. Then there are two other files. One is your flash "program", which is what the PSP will execute in order to access the flash memory. That is the important file. It weighs in at about 3mb. The other file is the flash file to be written. That is also important but it's only going to be handled by the flash writer.

I'll write more when i get back from work, I'm late!

d.x