Neur0n has released his 6.60 ME addon for Time Machine, a homebrew app originally released by Dark_Alex. Time Machine takes advantage of the Pandora Battery recovery setup by allowing you to boot firmwares located on your memory stick. Through this, you can use that firmware as if it is installed to your PSP's flash memory, change the default settings and customize it as you please. Apply all of this to 6.60 ME and you'll be able to play games that require a higher firmware and use 6.xx plugins without leaving the comfort of your original firmware.
The downside to this however, is that PSP compatibility is limited by Time Machine, which is limited by Pandora itself. This will only work with Phats and Slims that do not have a TA-088v3 motherboard inside. (The TA-088v3 motherboard, PSP-3000s and PSP GOs will not boot into the Pandora Battery recovery menu) If you're lucky enough to have a compatible PSP, you can give this a shot. Remember, you will need a battery converted to function as a Pandora Battery and a memory stick that is properly formatted as well.
