I have a lab mix that just loves to go with. I've shot a few squirrels when he's been along, and he definitely "gets it", although he's never actually treed a squirrel.

What is the best approach to squirrel hunting with a dog in a woodlot situation?

Most of the squirrels I've shot over him are "big woods" situations where I'm moving, see the game from a distance going up a tree, simply walk over and kill.

Any advice would be appreciated. thanks

Unfortunately, most really good squirrel dogs tree naturally. Sounds like your's doesn't. Teach him to tree by taking your freshly killed squirrels and having him track them down. Make it easy at first and slowly progress. When he sees the squirrel (make it some place real easy at first), talk to him excitedly and try to get him to bark. As soon as he does, give him the squirrel for a couple of seconds, then take it away and lavish praise on him. With LOTS of work, he may become a decent squirrel dog.