like any foreign stock, the dividends will be paid in local currency (canada) and credited to a US account translated into dollars. Ditto with the stock itself, it trades off the canadian price plus or minus the exchange rate... root for a strong Loonie!!!
Unfortunately so far the dollar has been strong. The only drawback of holding in an IRA is you lose the foreign tax credit on withholdings. Not enough to keep me from not having a few shares in my Roth IRA.