PsDev who many in the PS3 Homebrew Scene know as the author of several works such as PS3Wizard has created a very simple yet handy homebrew app called Ps3 CFW Folder Check.  This will help you get your CFW on a USB drive.

PsDeve mentioned that he was bored so he whipped this up in about 5 minutes.  Basically what it does is gives you confirmation that any folders you have set up are named correctly.  This will cut out any wondering you were doing on why the PS3 couldn't find your update.  He included the source code for this app too.

All you have to do is put the .exe in your flash drive where the folders are and run the app.  It let's you know if there are typo's or incorrctly named folders.  You can also confirm the pup name.

Source