It's fairly straight forward I believe, not too different from a normal HSF. With your board its just some springy push pins holding it on. Loosen those off. Some north-bridges rely on sticky thermal tape / paste to hold them on. I believe with the pins you could just use a mild application of AS 5 or other good quality TIM (using too much could have this stuff squeezed onto the motherboard... you don't want that) under the aftermarket cooler, then fasten the cooler into the north-bridge with the pins if it has them, otherwise you need the sticky thermal tape / paste.
Take this with a grain of salt, as I haven't done it personally.