How about an RS232 to bluetooth adaptor:

[Link: expansys.com]

I would think you could use this adaptor and suitable PC software to view the codes transmitted by Sony's PS3 Bluetooth remote. Then you could connect the adaptor to the RS232 ouput of a universal remote (e.g. Pronto TSU9600) and send the relevant Bluetooth commands direct to the PS3.

However, I don't know enough about Bluetooth/RS232/PS3s to know whether this would work - can anyone else comment?