PSP1001/ 01g with 5.51 OFW: Can I/How do I Install Modern CFW?

[Alakazander]

Like the title says, I have an old PSP with some old OFW, and I'd like to put some CFW on it. So, do I have to upgrade then downgrade my FW? Use a Pandora battery? Or worse yet, am I stuck with only M33 and GEN? (Well, maybe it wouldn't be that bad.)

Or is it something as simple as this:

Since you don't have any CFW or HEN installed,
- First, download this, and put it on your /PSP/GAME/ folder
- Then run TN-A installer from your XMB
- After that, check your System Information, make sure it was 6.39 TN-A
- Download 6.39 Official Firmware, extract, then rename the EBOOT.PBP to 639.PBP
- Copy 6.39.PBP to /PSP/GAME/UPDATE folder (create if you don't have one)
- Next, copy to EBOOT.PBP from the ME-9.2 UPDATE folder to the /PSP/GAME/UPDATE
- Unplug your USB cable, then run the installer from the XMB(not the TN-A installer).
- When you've done, check you System Information again, it should be 6.39 ME-9.2 or something.

Thanks in advance meganova/Zorlon/Jazzmarazz/Kouen