Ok this wasn't as hard as I thought.
- follow the instructions here to change the C++ library
- remove your libQCAR.a and headers in your build folders and replace it with libVuforia.a and headers (you all likely did this differently than I did so I can't give an actual example)
- change your build targets to include arm64 and standard architectures (you'll see it) Don't forget to do it for both your adhoc and appstore releases
- search/replace all instances of ImageTracker with ObjectTarget
- change the definition of targetPositiveDimensions from Vec2F to Vec3F
get an app key from Vuforia, look for QCAR::setInitParameters, and add a second parameter with that key as a string...
QCAR::setInitParameters(mQCARInitFlags, "my license key");
I think that's all I did.