I thought they were to be honest since I looked at the ram earlier,
I'll try tracing the IO but the game uses async functions which makes it more difficult
Edit:
http://ebitsu.net/archives/9987896.html
Interesting but I don't think it'll be ZZT4
Edit:
Okay some good and some bad news, I found where the images are stored which is
in PSP_GAME\USRDIR\DVDROOT\LAYOUT\TITLE_MENU.TPL.
The problem is the file is a compression archive so you have to figure out how to decompress the file, split it, edit the files, then compress and rebuild the archive with the right structure.
As a wild guess its some form of LZ77
Now for a successful full translation I'm guessing a tool will be needed to:
-decompress the content
-split the .tpl into files
-import replacement files and update .tpl structure
-recompress content
I haven't looked at the asm in detail yet but honestly, without an existing tool that works programming compression could be very difficult
It might be possible somehow to asm hack out the comp sequences, and store all files as raw but in this case I'm not sure if this is viable either
I've attached the decomp file dumped from RAM, if you run the tool on it you'll find the menu items incorrectly labeled as ERROR (all the files actually open fine), the choices are 2kb each
Oh and the correct interlace for the large images seems to be BGR+I / BGR