Just sketched up a simple board with an AT90USB128X/64X that has enough I/O for programming the NOR flash on the PS3 Slim.
Have not written the software yet, but if someone would find it useful then here you are
1. Make the board
2. Solder it on to the NOR testpoints according to git.fail0verflow.com Git - noralizer.git/summary
EDIT: the failoverflowgit is now offline, so I added the flasher files.
3. Write the software
BTW, a Teensy ++ 2.0 would probably work aswell.
The software should be only a few hours work, will probably get to it in the next few days. The excellent lufa-lib should be a good startpoint for the USB part, and the flash programming routine is quite straightforward.
The flash memory is either S29GL128P or K8Q2815UQB ( and perhaps more versions exists ).
The Board is only one layer so manufacturing should be quite straghtforward.
Made with Eagle Freeware (CadSoft Online: EAGLE Layout Editor)
Thanks goes to Hector Martin
Now with the actual files..