I'm not an expert on bluetooth by any means, but I think you'd need some sort of network capture tools to save the signals that that the normal PS3 bluetooth remote outputs.

something similar to capturing and recording IR signals from IR remotes.

Then, if it seemed possible at that point, you could knock up a python+bluez application that would push the same signals over the bluetooth connection.

Oh, and you'd have to get the PS3 to pair with you tablet as well.

It might be possible, but I think it'd take some work.

I'm sorry I'm not more of a help :/