Assuming this is a private airplane that is transiting Canada, the customs clearance procedure is as follows:

1. The pilot-in-command must personally call CBSA's Canpass center (1-888-CANPASS) to provide advance notice of the arrival in YQX. The PIC will need name/date of birth/citizenship/purpose of trip/length of stay etc. for everybody on the plane, plus the plane's tailnumber, ETA, and FBO at YQX. This info must be given to Canpass a minimum of two hours prior to arrival and a maximum of 48 hours. The ETA of the airplane must be within the hours of operation of the customs office at the airport.

2. Upon landing in YQX, plane should taxi to the designated fbo and call the Canpass center again before anybody opens the door. The officer will either release the airplane over the telephone and give permission to deplane, or instruct the PIC to await the arrival of "local" customs officers, who will check passports and do a primary inspection of everybody on the plane, and possibly a secondary inspection as well. If a customs officer is at the fbo awaiting the arrival of the airplane, the second phone call to Canpass (i.e. after landing) isn't necessary.

It's the same procedure for a tech stop as it is for any private plane entering Canada.

If there will be more than 15 people on the plane, the CANPASS system can't be used, and arrangements must be made with the airport's customs office to have officers meet the airplane.

I should add that all of this is in addition to any exit requirements that US Customs may have (e.g. eAPIS)