New Version

There is a completely new version that adds the Engine to Perforce in a completely different and much better way. You can read about it here:

http://allars-blog.ghost.io/2017/04/05/populating-perforce-with-an-unreal-engine-source-build/

Video Version

Condensed Version

If you know how to use Perforce, basically...

Make all the .dlls and .pdbs writable in Engine/Binaries, Engine/Plugins, Engine/Programs, YourProject/Binaries.
Don't put any intermediate files on the server.
Don't put any DerivedDataCache and Saved folders on Perforce.