It's not that hard in Arch Linux. You get the PKGBUILD for original package, and run makepkg once with an option to just prepare the src/, then you can modify i

It's not that hard in Arch Linux. You get the PKGBUILD for original package, and run makepkg once with an option to just prepare the src/, then you can modify it and then you run makepkg with a flag to skip the src/ preparation and finish the build. Just to change the build/configure flags, you can simply edit the PKGBUILD. Nothing fancy, I've been building firefox this way to disable signing requirements for extensions, until I gave up on firefox extensions completely, because of the general unfriendliness to developers with the signing requirements that can't be disabled without wasting a shitton of electricity.