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Thanks for asking.
Bluetooth works very differently from f.ex. Infrared. Put simple, it's
a protocol that embraces a client/server/connection concept enriched
with elements of what most might already know from USB devices. At the
most basic level, that includes a vendor and product ID as well as
unique address (the BD Address), all of which can't be changed or
spoofed, which would likely be a necessity to get the Bluetooth device
get recognized by the PS3 in the first place.
I therefore don't believe that this is possible without additional,
specialized hardware. Logitech plans such a device for their Harmony
remotes:
http://blog.logitech.com/2009/03/20/caught-were-going-to-provide-you-with-logitech-harmony-ps3-blu-ray-control/
Best regards,
Felix Schwarz