Step 1: After downloading the File below, Take a USB drive (at least 1GB) and plug it into your Computer.
Step 2: On the Root of the USB if you havent already make a folder called "PS3" (No Quotes" and open it. Inside that folder make a Folder called "UPDATE" (No Qoutes) and in this folder copy the FERROX_450_100.PUP
Step 3: Rename the FERROX_450_100.PUP to PS3UPDATE.PUP and then exit the USB and plug it into your PS3.
NOTE: There is no need to Update your SingStar MultiMan or Multiman yet but you will not be able to play yout Game Backups untill you do.
Step 4: On the XMB go to System Update and click X then go to Update Via Storage Media, Locate the 4.50 PUP and click X again. Allow the data to copy to the HDD and then hit the PS Button and resume the Update.
When the Update is done you are now Running CFW CEX Base 4.50 V1.00 FERROX