According to td ameritade:
You can trade Canadian stocks by trading the U.S. over-the-counter equivalent. These trades can be placed online, through our IVR phone system, or with a broker. If a Canadian stock has no U.S. over-the-counter equivalent, you can place a trade by contacting a broker. Please note that there may be additional fees for trading sizes that do not constitute a 'board lot' in the Canadian market. A broker can provide you details for specific stocks.
I have no idea if tweed will have an OTC equivalent??? What does this even mean.