To put t bluntly no the is no USB mods after W@W you need to have a jail broken PS3.
DEX - this is term given to a PS3 that was designed for testing and developing things for the PS3 platform. Obviously people can change there retail console to this now meaning that any console capable of CFW can be a test unit.
CEX - this is your console this just means it's a retail console and that is all which accounts to nearly all PS3's that people have and all the ones you find playing online games.
CFW - this is exactly what it means. CFW is an abbreviation for Custom Firmware meaning a Firmware that was never released by official means and is created by someone within the community.
Now down to your next issue firstly you need to see if your Console can be jail token (which would mean having to open your console, attach a flasher/programmer to your NAND/NOR chip and then creating dumps and altering them to be able to Downgrade to 3.55 so you can Jailbrake.
So first off turn your console around so you are looking at the back if it and you should see a thin white sticker with a barcode on it and a long number and letters.
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Now what you need to look at is the final part of the serial number and find the last couple of digits and compare it to the chart above to see what YOUR model of PS3 is and what is the earliest firmware it can go to. If it is higher than 3.55 (or maybe 3.56 in some cases) your out of luck. If you can go to anything below 3.55 then you would either need to purchase a hardware flasher (E3, Progskeet, teensy++) to do the rest of the process or you can find someone who could do it for you BUT before thinking great I can do this be careful. Especially if you are willing to send your PS3 off to someone because after they have your dump they also have access to your console ID meaning they can use it to get banned PS3 console back online and the end result yours WILL BE BANNED.
Just think carefully.
If you have any other questions ask away.