The frame pack you refer to(DJs Frame Pack in Make Your Own Section) has plenty of room for a bear cannister inside the bag. No need to lash it on separately. It fits in the bag nicely, laying on its side.

On the Olympic National Park coast they allow 5 gallon buckets for food instead of bear cannisters. The 5 gallon bucket is too big for me to put it in my pack sidewise. It fits nicely standing up in the pack, however.