Tried it with 256MB NAND PS3 and it works, although I didnt use anything related on otherOS PUP's. Just a plain LV2 patch to load Linux.
All process were done on linux, from dump the NAND >> Extract >> metldrpwn >> patch the NAND for DEX with the EID0 gained in metldrpwn >> flash the DEX.
After that, turned off the console and turned back on. As usual it boots, and began installing DEX firmware.
Mentioning that I didnt loose a single save file nor a game data or PSN games currently stored on my PS3. All games works as usual, PSN games dont work though since the keys used on those PSN games to sign is probably already blacklisted anyway.