Sorry, but AC doesn't have points upgrades for Aeroplan members, and I don't believe you can use your Mileage Plus points for that type of award either. Only SuperElites can upgrade on discounted international fares with coupons issued to them every 10K of qualifying miles. This would not be extended to UA members, even 1Ks. The only possibility is if the flight is overbooked and they must operationally upgrade elites. Obviously AC's own elites will have priority over other STAR Gold members.