You'll need to get familiar with Git and Repo as well as How to build a GSI.
Run the following:
git clone https://github.com/kaii-lb/treble_everest.git
cd treble_everest/
sh patches/apply.sh [rootdir] [patchdirname]
sh patches/apply.sh [rootdir] [patchdirname] --reset
to reset a patch directory to default. RESETS ENTIRE DIR!!!sh patches/apply.sh [rootdir] [patchdirname/specificpatchdir]
to only apply a certain patchset ie: trebledroid/platform_frameworks_base
If you face any conflicts while applying patches, apply the patch manually. For any other issues, report them via the Issues tab.
These people have helped this project in some way or another, so they should be the ones who receive all the credit: