It's already in there - the 1.12.0.0 release (Jan 4th) from the AB automatic updates includes it, create an Eldar roster with Imperial Armour enabled and under Fast Attack there is a Hornet Squadron unit, add that to your roster and then use the unit options at the right to add additional Hornets as required.
And as usual, any requests or bugs should be directed to
http://www.ab40k.org