There is no current method to jailbreak any ps3 with a firmware above 3.55, with a downgrading process that involves a hardware flasher. This involves a E3 (best for NOR) or Progskeet (best overall flasher, especially for NAND), and soldering them to the motherboard inside your ps3.
You will first need to ensure your PS3 isn't one of the newer revisions with 0.2 key revisions, or was released from the factory above 3.55. The console can only be downgraded to the lowest firmware it was shipped it. There are no-solder options for both the E3 and Progskeet, but they gimmicky at best, and can be a bit troublesome.
If you don't have soldering ability, I would recommend finding someone who can do the entire downgrade process for you (it can be quite overwhelming for a newbie), or finding a ps3 already on 3.55 through Craigslist, Ebay, or another similar trading site in your country.
You can keep your current ps3 for online activities (or brand new games), or sell it. Keep in mind, the majority of the time you will have not have PSN access on any ps3 with custom firmware. Occasionally, there will be a small time frame where you can, like right now with the recent news.
Last edited by stock2255; 09-12-2012 at 01:30 PMReason: Automerged Doublepost