Until a few days ago, I thought:
a) Messiah was to-good-to-be-true
b) only a 'select few' had access to these chips
c) the chances of getting one installed on your PS2 painlessly were next to nil.
Well today, I still believe these chips are in short supply but I've been proven wrong (thankfully) on all other counts. So big thanks to charlie_ps2 for getting me up and running so quickly :-)
If you're considering outfitting your PS2 with a Messiah then I strongly recommend talking to charlie (and his mate round the corner)