It can be done, but it all goes back to the old saying:

"Good, fast, cheap. You can pick any two."

For best results, you'd want to rebuild your motor to better support the ethanol. Start with higher compression. 12:1 would be about right. Next, you might have problems with rubber / plastic components in the fuel system. It is set up to work with 10% ethanol, and I doubt you'd have a problem on 85%. But be advised you might have to change a fuel pump and some lines, possibly injectors too. Some sort of intake manifold heating is highly recommended to get the ethanol to vaporize correctly.

Speaking of injectors, you need to put more fuel in with E85. The proper way would be to have a custom computer chip programmed for ethanol, and use a couple sizes bigger injectors.

You could probably just dump it in the tank and run it the way it is now, but your mileage will likely go down enough to negate any benefit. Plus, you'd likely have cold start difficulties.