I'm needing some encouragement now.
After several months of struggling, Cody and I are biting the bullet and going straight to briefs during the day. Lee knows how to use the toilet, he knows when he needs to use the toilet, and he has the vocabulary to put it all together. He just needs to be more uncomfortable wet than dry, and he needs to want to use the bathroom.
Today is day 2 of our straight-to-briefs method, and so far it is going well. He went one pair of undies yesterday, and did his "business" in one today, but otherwise, he's stayed dry. Hooray! He gets a smiley face on his chart when he tries, and he gets a treat from the drawer next to the toilet when he goes.
I must remember: this will all be worth it. He will figure it out someday. Accidents happen. Be patient. If I can conquer this, I can conquer ANYTHING!