This article, a 38 page .pdf file from the William Mitchell Law Review (37 William Mitchell Law Review 132-169 (2010)) discusses the general process for obtaining Medicare coverage for durable medical equipment (DME) and the specific requirements for Medicare coverage of power operated vehicles (POVs) and scooters used as wheelchairs, including the Advance Determination of Medical Coverage (ADMC). You can read the article at http://www.wmitchell.edu/lawreview/Volume37/documents/Chiplin.pdf.