HI!
Assuming you want to DIY, you would need to start with the accelerator, from there you can use a microchip to decode it from acc data and encode it to serial data to send it down the bluetooth pipe(there are other protocols available but thats prolly easiest, from there you will need software on PC side to receive the data, decode , and decide what it is goin to do with that information.
A quick search for bluetooth acc returns lots of gadgets for sale that take care of the hardware side of what you want, then from there its software.
What kind of rotation are you thinking?
just basic portrate/landscape orientation or per degree?
.. depending on the complexity of requirements you may be able to use prebuilt functions in programming or may need to diy it, what is this for , a game, or more of a background worker?