What it takes is the SHSH Blobs of the firmware that you'd like to downgrade and pick your iPhone 4 or iPad 2 that runs on iOS 5.0 or iOS 5.0.1 and then downgrade it to the firmware of your choice.
NotCom further saying that the TinyCFW is not TinyPwn, the tool he once promised to release someday.
Here is things you need to know about TinyCFW:
What is TinyCFW, using tool you will be able to modify an existing ipsw that is released for iPhone gsm/cdma 4 and iPad 2 gsm/cdma
And it will also modify the iPSW to update your basebadn to the latest. And so creating the iPSW that you can utilize with TinyUmbrella and then iTunes to restore to a iOS version that you own the SHSHs for. And the tools is for iPad 2 with a baseband and iPhone 4. You can read more about it via NotCom blog here.
Download TinyCFW (Mac OS X)
Update: here is a tutorial on how to downgrade your iPhone 4 or iPad 2 based on iOS 5 firmware to iOS 4.3.3 using TinyCFW tool.