411 REFERENCE · Wikibooks
PSP/Install 6.60 PRO
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Download 6.60 PRO-C.
Extract the file.
Copy the contents of the extracted folder into the root of the Memory Stick (ex. PSP -> ms0:\PSP, seplugins -> ms0:\seplugins)
From the XMB (main psp menu), run PROUPDATE from Game - Memory stick.
Press X to install CFW.