I got a plug-n-play converter box from here:
http://www.change2e85.com/servlet/StoreFront

The claims on the site are a bit overstated.
However, it does work.
My otherwise stock FEH runs great on E85, just with lower MPG.

The built-in Ford ( or any car ) ECU has the ability to change the injector pulse length between -30% and +30% from "normal" fuel/air ratio of 1:14.7 for gasoline. ( to adjust for load and altitude for example )

Running at +30% is 'almost' enough to run E85. In fact, your stock, factory FEH can run up to E60 right now.

However, to run E85, you need the injectors to fire +35% longer.
If the ECU tries to pass 25% the computer says, hey, this is unusual, something must be wrong, and a check engine light comes on.

So the factory possible range is about -30% to +30%.
( with -25% to +25% considered "normal"... or up to 29% in a 2008 )

Here's what the "add on" E85 box does:
It moves the injector range to -15% to +45%.
The car's ECU still controls everything in the car.
Ford's software is in full control of the air/fuel ratio, and emissions control.
Just now -15% to +45% is now considered the new "normal".

It was much simpler than I expected to run E85.
No hardware change is required.
Just a software "spoof" basically.
-John