Luis can correct me if I’m wrong, but I believe the official CacheBox code is what lives in /system/cache/.
I think Luis just has a custom build script that pulls that out and creates the stand-alone CacheBox download. There are no code differences that I know of between CacheBox standalone and the CacheBox that comes in the ColdBox bundle (except for maybe the package name in the code).
If I am correct in my assumptions, then to contribute to the CacheBox code would mean you forked the main ColdBox repo, modified the parts of CacheBox that you wanted, and submitted a pull request back to the main repo.
ColdBox Platform Evangelist
Ortus Solutions, Corp