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