And with that, I think I'm not going to work on this.
Not because I'm unable to do it in terms of skill, but because I'm unwilling to accept large blobs of code into the codebase without having a developer that supports it and takes care of issues that come up.
To be clear on this, we could do it, but it would take a lot of work getting into the codebase, then merging the forks, then squashing all the bugs that appear. If the original developer is not available to work on this due to other commitments, this becomes very hard. There was a similar situation with post processing; We finally got that resolved in antipodes 6, but even that took something like a year.
Good luck with your own engine.