I like your idea of the lunge line, I think that is a great idea. Personally, and from all of the behaviourists I have ever worked with, come is the #1 most important thing for a dog to learn. Multiple treats when he comes (throw one, let them eat, throw another etc) and make it lots of fun to start. If they are hesitant, make it interesting for him (bend over and slap your knees, dance back and forth, wave your arms), basically look like a goof but be happy and then big rewards when they come back. As he improves with his recall, you can begin to enforce your rules (one time call or whistle etc). Don't expect him to come right off the bat when you start out because more often than not, you end up with expectations that are too high. As with any animal, always end on a good note (so a shorter recall if that is something he is successful at, or a sit, stay, down etc). Also, keep your "training" sessions short. Only work on recall for 10 or 15 minutes max in terms of actual "training." Good luck!!!

(and where are the photos?????)