I found it a doddle in my k series.
Take off the rad cooling fans and pop off the bottom hose of the rad. Undo the bleed screws in the heater matrix and the is one further down under the air filter, which I'd advise to take off as well. Then fill it up and close bleed screws when you get a consistent flow of water and that's pretty much it. Put back together and pray :D
DT.