How to use Sloth and Torpor as an object for meditation

The Satipatthana Sutta details the use of the sloth and torpor hindrance as an object for mindfulness meditation. Does anyone have any practical advice, either of a personal nature or from an established teacher, about how this might be achieved. Whenever I am suffering from this hindrance it completely negates any attempt at meditation of any sort. So I am interested about advice how tiredness could be used as grist for the meditation mill.