I had a crack at this because my son just loves iced coffee.  It was so easy and really yummy.  
2 x teaspoons any mocha coffee granules - I used the Nescafe Cafe Menu one (3 teaspoons if you like it stronger)
2 x scoops vanilla ice-cream
half a cup of milk.
Blend on speed 7 ten seconds.
This makes a smallish glass so you could either times it by one and a half or even double.