Is doesn't take a degree to grill a brisket, just a good plan and a little experience. Stack your charcoal and let it burn down until it forms ashes, and use wood chips to smoke the brisket. You want your constant temperature to be at 225 degrees fahrenheit. The temperature may vary a little during the cooking process, but you want to come as close as possible to this temperature at all times.
Remember to open the grill vents to increase temperatures when you think the grill is cooling off too much, and close the vents to lower the temperatures. If you follow these steps, you can be almost assured of having a very good brisket.