Gotcha. You want to build his ability to pay attention to you in the presence of other people, and you can accomplish this with treats if he's food motivated. Just remember to use crazy amazing treats he never gets; it's just for when you're having people over.
I would emphasize a couple different exercises: -reward him for looking at you and for sitting before people walk in -when people walk in, they are to completely ignore your dog until he has self-control (5 minutes? 10 minutes? 30? Where-ever you start is where you start). No looking at him, no talking to him, no touching him. Make sure they understand before they come inside; it'll be hard to explain once you're dog's all worked up -let him say hi with a quick sniff and walk him away. Reward with LOTS of praise and yummy treats for coming along with you -- otherwise, it's just you dragging him away from awesome new people. Again, the people he's sniffing are not giving any attention at this point, as it'll just get him all worked up -you can let him go back and sniff as often as it seems appropriate. The instant he starts to get wiggly and excitable, walk him away and reward for coming along with you. Or if he starts to jump up and smother with kisses, walk away. -your only punishment is walking him away. He's probably not going to listen to anything you try to verbally communicate, and you're trying to model calm behavior for him. You're just trying to get across that getting worked up gets him even less attention but... -being calm and having self-control gets him more human interaction -from here, if he's doing well, practice having him look at you (for treats) in the presence of house guests -if he's doing well, let them look at him and quietly talk to him -if he's doing well here, let them calmly and briefly (like 3 seconds) pet him -at any point you're trying to push it to the next level and he loses himself, walk him away for a moment
Start doing this at a very easy level for him -- just one person or only two? Also, you could blow through all stages of these exercises in one sitting, or you may find it takes a couple of visits with the same people before he has more self-control.
Let me know if I can clear anything up!