Not to be calling anybody out but it would have been legal any year as long as wireless devices go....Who said you
must use the blue tooth. The data has to be sent to the blue tooth transmitter somehow. Now the question is whether you want to spend the time reverse engineering the device. Also if you go with the latter option you need to see if the time you spend on the device is worth the money you save. Even if you do use blue tooth. There is blue tooth support for the 07 controller, you need to go buy something to interface to the controller though. (there is support for anything, just not all of it is built in
)
EDIT: Or better yet......Just take the sensors out. unless they have that weird hard thermal plastic stuff on it. And even if it is SMD just do hot air rework on it. You can easily make your own PCB.
-John