You use the same plastering spreading technique but you really need to apply some bonding material to the bricks before applying, such as diluted Unibond. The mixture needs to be a little wetter than ordinary bricklaying mortar and don't try to do too large an area at once.
You need to put on a stratch coat first, which is a sand cement and water proofer mixture, around 10mm when you put it on you scratch in a key before it goes off.
Once this coat is set you wet it down then you put on a top coat of render smooth offf then rub up nice and flat. it is verry important you pick the right day to do this, ie no direct sunlight or heavy rain.
Good luck.