The motor shafts are threaded. All you should need is a 4mm to 8mm spacer. The slow-fly props usually come with adapters. After you bolt on the prop you will want to dremel off the excess shaft. Wrap the motor in a plastic bag so the filings don't end up in the windings and magnets. Leave a couple mm above the prop too.
You may not get the performance you hope to out of the E-props. They are usually a little heavier than a good slow-fly prop. The extra weight translates into sluggish changes in motor speed. Since we are relying on the change in motor speed to control the attitude it will mean sluggish response. Most people have gone back to APC slow-fly props. They seem to be the best in endurance and the best trade-off for weight versus stiffness.