EAPIS. File a flight plan (IFR or VFR). Call Canpass, give them the details they ask for, and they ask you the declaration questions over the phone.

When you land in Canada - if it is a big airport with full time customs - you taxi to the office. Otherwise you taxi to the customs area and if no inspector is there call Canpass again and they say "no inspector meeting you today, here is your clearance number".

Coming back is pretty much the same but no canpass and you can fill out your declarations at the AOE. Just taxi to the customs area. I make it a habit to have the phone number of the customs office I am landing at and call them to update an arrival time, even if it is going to be the same as I filed in the EAPIS. They seem to appreciate that.