At WestJet, we have a few ways of doing things, as a manual back-up, for when the computer systems occasionally "go down"... we can do manual boarding passes, and seats are done "festival" where basically we board people by check-in time, and then it's first come first serve on the plane, similar to how Southwest boards. There is also a sheet, which has the seat map of the plane on it, and each seat is a little sticker, and you can just peel off the ones you want to use, and affix them to boarding cards. One a sticker is gone, obviously no-one else can take that seat. Both systems work quite well, and don't require any technology really, just paper and pens. Then we do head counts, and match them against boarding card counts. Quite simple really.