Disklavier

I'm looking for any books/websites/advice on how to write piano 
transcriptions. I've looked everywhere! No luck so far.
I am completing my first major transcription project and I have 
countless ideas for many others ( maybe even a great virtuoso 
transcription someday! ). 
I'm classically trained, but not extensively so I think transcriptions 
could be my niche in music. If it doesn't work out commercially I'd 
still like to do it for fun.

thanks in advance,

Eli