Can I transit through Shanghai without a visa flying with my retired airline employee pass?

Dave, do you mean you will fly from Vancouver to Shanghai using your standby passes and from Shanghai to Phnom Penh with a confirmed ticket? If so, as long as the airline in Canada allows you to board onto the plane, you can make use of the 72-hour free transit policy and don't need the transit permit under the condition that your layover time is not more than 72 hours.