There has already been done a bit of work and discussions on that topic. The reason you have not found anything on that matter is because we discussed this in the internal board. Matthes allowed us to develop the openclonk league based on the clonk.de league code, but for security concerns only in private (for now).

Looking at the thread in the internal forum however, there is not so much useful information there (that still holds, a lot about password hashing, SSO etc. ... which is obsolete now) so I don't see a reason to move the thread into developers corner.

Function- and code-wise, the "OC" league is pretty much still the same as the CR league. Instead of a valid CR registration, one will just need a forum account on openclonk.org and can use the same data to login to the league (yet to be implemented by the league).

If you would like to help, that would be awesome! As said, to get it into a releasable state shouldn't be too much work but it would be great to have someone like you having ideas and being interested in developing the league further.