From what I have heard it may be impossible unless 3.60 keys are released. I could be wrong, and portal 2 isn't out for another week I think so I dont think your suppose to post about games that are not out, but your choice.
Any way I hope im wrong becuase when I buy this and other new games that require 3.60 i hope I can play them on my J.B Ps3 3.55
Ps3 Slim CECH-2003A Rebug 3.55.1 F.W + OtherOs
120GB Internal HDD & 500GB External HDD
Gaia 2.07 & multiMAN 2.00.3
PS2 Silver 50003
Free McBoot 1.8
What more could you want!