B-ZaR said:
Nope, you don't need a sensor bar if you have the motionplus addon. I've hacked together a plugin to use a motionplus-enhanced wiimote as a quite accurate air mouse for cwiid. I haven't gotten around to releasing it yet, but anyone interested can give me a call.
You don't need the sensor bar even without the motionplus. It provides different functionality than the accelerometer (though it can be used to correct coordinates in 3d space if you assume that the sensor bar is horizontal).
f you've been working on wiimote stuff you should know that the wiimote can be in different modes, you can't even have full IR data reporting and extensions (motionplus F.E.) on at the same time, there's not enough room in the packets.