The only way to know the answer to your questions is to ask a Canadian immigration law firm as few US firms, wihtout a Canadian partner would deal with this. The provision is TRP not TRT and this is the little I found from one of the Canadian firms that advertises on the internet:
Immigration officials determine whether a temporary resident permit can be granted, and the reason for which a person needs to enter Canada will be factored into the decision. Justifications can vary, such as entering for business or work purposes, seeing family members in Canada, or being required to transit through Canada to travel elsewhere.
The other method, called rehabilitation requires the passage of 10 years since the conviction with no other criminal record and not all DUIs qualify for it. So your best chance is the temporary resident permit.