How to enable LPE and attitude estimator?

I am trying to enable the local position estimator in pixfalcon. I read that the modules/local_position_estimator and modules/attitude_estimator_q are commented in the px4fmu-v2 file and has to be uncommented for it to work.

Question is, how do I build and flash the code to pixfalcon after changing the cmake file? Any detailed instruction such as the command to do this would be greatly appreciated, as I am a beginner in using the PX4 and any related software. Thanks!

Build instructions are in the dev guide:

The command you’re looking for is

make px4fmu-v2_default upload

The Firmware 1.5.0 do not feature the LPE estimator.

The Firmware 1.6.0 RC1 features it as an alternative build, and is built in the zip file in the release tab from Github. You can upload it as it was a custom firmware from QGC