From the OTC Investor
""Getting started shorting penny stock is very simple – just ask your broker if they support this type of activity. Often times, discount brokers will allow clients to short-sell certain popular penny stocks, while only specialized trading firms will allow shorting of almost all penny stocks. However, these specialized firms often have higher commissions and/or a minimum number of trades per month in order to quality. Finally, investors should also make sure they have access to real-time level II screens.""
I would have thought you would have known this?