Mill a small amount of grain and grab yourself a small mesh bag like you would use for hops or steeping grains and add the water around 158F. Then the trick is to keep it at the correct temp which you can do in a water bath on the stove or I sometimes use a small drink cooler. Once 30 min or so is up I press the wort give it a quick boil and do what I want with the wort. I only suggest a higher mash temp because it will likely be such a small amount of wort that the sugar profile won't have a noticeable effect on the beer, and the higher mash temp means mo' fast conversion.