Well....
If you're going to play with the sharks, you can't be afraid of the water and have to join the feeding frenzy.
I'd suggest doing up a 20pg screenplay spec, with an outline of where you're going, then contact the writer (the publishing house more than likely has only the rights to literary media) and send them what you have so they can determine if you've hit the mark on what they're looking for. You might be surprised. Everybody wants their work on film and if you do a fabulous job putting their baby out there...it does happen.
Good luck.
p.s. Before you send anything anywhere, make sure you work it until it's perfect, join every screenwriting board available and get as much feedback/critique as possible and then, if you really want the chance to write the sp, make the changes suggested and post the final product before sending it out.:hat
If the writer (novelist) decides he/she likes what you've done with their work, get an entertainment lawyer to draw up the agreement.