The JS source is at https://github.com/siravan/moonjs.

It's derived from Ron Burkey's unmaintained Virtual AGC at http://www.ibiblio.org/apollo/, which also hosts many of the manuals and related documents.

But if you really want to be cool, you could build a real AGC from scratch: http://klabs.org/history/build_agc/

I've tried to play with that before, it is pretty incomprehensible even after reading the descriptions and Wikipedia article.

I feel like the source is likely clearer than that interface...