Working directly with the MPU-9150 Chip

I'm trying to understand how to initialize the 9150's DMP in order to receive the benefits of "Motion Fusion" from all 9 axes and readout this as quaternion data, as promised in the sales literature. However, it appears that the details of how to do this are buried inside the MotionFit example code and, unless I've missed something, not really described anywhere else. What i'm looking for is something along the lines of an App Note that details how to initialize the 9150 and its DMP, calibrate it and then configure it to spit out motion fused quaternion data. My application is to use the 9150 as an AHRS, so I'd like to have the DMP perform the motion fusion for all 9 axes, including the magnetometer. Can anyone point me in the right direction? Or, am I have to figure all this out by reverse engineering the demo apps?

Wayne