I've searched here and beetleforum extensively, and I have not found any guides to making rotted leaves (though wood fermentation instructions are rather common).
Here is my attempt, which some of you roachkeepers may find useful. Currently they have been freshly put into containers, so I will update as time progresses.
https://sp-uns.blogspot.com/2018/02/i-attempt-to-synthesize-rotted-leaves.html