This one took quite a considerable amount of time to get working.
I am using kmeaw 3.55 Custom Firmware with the multiMAN 01.13.01 backup manager.
Eventually I got mine working by firstly transferring from PC > PS3 (Gran Turismo EU v1.00) using FTP blackb0x for example
Ensuring the permissions had been set correctly by downloading:
Dashhacks :: PS3-Hacks :: Fix Permissions - Install the package and then run it.
(Incorrect permissions are sometimes assigned by the FTP software you use on your PC which is incompatible with the PS3, it causes black screen when you load the game - this fixes it)
Then I followed the update and EBOOT patch as detailed below:
Then I LVL2 patched my PS3, inserted any origional PS3 game, ran multiMAN, loaded Gran Turismo 5 from the multiMAN, returned to the PS3 menu, and ran the game by selecting the disc in the PS3 menu