ASSUMING that the amp is OK with a 2ohm load then you "set it up" by the configuration of the speakers you use. Two 4 ohm speakers if parallel will give you a 2 ohm load. However, if you are bridging the ouputs then a single 4 ohm speaker bridged between the two outputs will put a 2 ohm load on each channel. Be very careful if you are bridging the outputs that you know what you are doing. On average, when bridged wrong (too much load) the amp will last about one month before it fries. Get some help if you are bridging. Be sure not sorry.
Usually answered in minutes!