If you speak french, see the Chocobozzz response here: Procédure pour intégrer des modifications customs à son instance?
If you don’t speak french: there are 2 solutions.
- Use the nightly build (at your own risks) https://builds.joinpeertube.org/nightly/
- Clone the git repository, apply the patch on the latests stable tag, « npm run build », copy needed folders on the server (see folder list in release.sh)