You CAN'T use a DEBUG PS3 on NP-INT (SEN/PSN).
What the guy suggested you was to hack it so it behaves like a normal CEX console after you run the patch (don't run that as it will screw the console a bit).
I suggested you sell it to a real DEV and buy a hacked CEX console which is way easier to use.
Also you can download official DEX fw on the internet (I think latest to be leaked was 4.30) but you can't go to PSN with a DEX console, period. (Exception is hacking to make it behave like a normal console. If you choose to do that follow playerkp420 post...).
SCPH-10000_GH-001 SCPH-15000_GH-003 SCPH-18000_GH-008 SCPH-30001_GH-005 SCPH-30000_GH-016(V4) SCPH-30001_GH-010(V4)
2xSCPH-10190, 2xSCPH-10350, 2xSCPH-10280
"**** j0 hackers!"
-Sjeep (As seen on TOXIC OS ELF...)