How should I go about designing a part to work with the MDB standard?

Hello, I am a somewhat newbie to ICs.. I have 2 boards fabricated under my belt (well.. another guy and me designed them together).. But that was with the bs2.

I say that so you sorta know where I am coming from...

Basically I want to create project that will:
interface a PIC with a vending machine dollar bill acceptor.

So I have 2 problems.. hardware and software..

I would like to get you'lls opinion on where I should start. I have already:
-scavenged the net for PIC > dollar bill hookup schematic. (found none)
-downloaded the MDB standard file (read all ~100pages long)
-purchased a dollar bill > AVR > computer device (engineer from this?)


any pointers would be great!