These are merely suggestions / thoughts about how to implement some of the conventions specified in the main README.
We can use the npm link command, but that forms another dependency on npm which would be nice to avoid, and it might be tricky on Windows and various build systems (few build systems are tested on symlinks).
Instead, we can create our own workflow like dependency-env link MyDependency /path/to/local/MyDependency that doesn't use actual symlinks, and instead places a plain text file ./node_modules/MyDependency.link containing the destination. Various build systems may not even need to be concerned with this. The main issue is that npm postinstall scripts don't know how to process this file and walk down to these "linked" projects to build them before our project is build. That is probably okay, because we may want to bypass the default postinstall process anyways so that we can maximally parallelize the builds. Furthermore, if we completely bypass the npm postinstall, then individual package build systems won't need to understand the .link convention, because our custom postinstall process will cd to the actual directory of MyDependency, and as always set the appropriate environment variables such as cur__target_dir and cur__install back in the original top level package root.