First of all: whether or not your build is gonna be succesfull depends on yourself.
But, if you do things right, you'll end up with an automatic gearing bike.
You'll enjoy every ride better than ever.
If you plan on building a Shift4Me, you can:
Just register on the Forum and you'll have access to all the files you need: the list of parts, schematic and 3D printfiles. A complete step-by-step build manual will soon be available.
As Shift4Me is Open Source, you're free to do whatever you like. So you can fiddle around with the Arduino scripts, or draw yourself a new design to accomodate the electronics... Register on the Forum to get just the files you need.