Notwithstanding the rhetoric, immigration law in Canada generally suggests you are not admissible with a DUI. If I may make a suggestion though if you'd really like to go to the meeting; fly to Bellingham or Seattle and drive to a land crossing. When you present yourself to the border agent, explain you're attending a meeting in Vancouver at your Canadian subsidiary and wait and see if he or she asks about criminal convictions. Be truthful.

If he/she turns you around, then that's that but you haven't spent as much money trying to get in on a flight straight to Vancouver which would be expensive. They may not ask you about criminal convictions, or may see it and not care.

Still, I think the rest of the advice is sound. The reality is you're not admissible without a waiver, even though your circumstances are clearly extenuating, so you're at the mercy of the agent doing the examination when you arrive.