Getting your dog to sit to whistle and face you no matter how far away he is is not as hard as you might think.  From my experience, you need to make this something that he loves to do more than anything.  Sitting means something good is going to come next.

Heel Whistle Sit

Start by blowing the whistle every time you stop walking when you are heeling.  Right after he sits, click and give him a treat.  Do this for 1 week, EVERY time you blow the whistle give him a treat, don't forget the treats.  Do not every blow the whistle during this time unless he is heeling, or in front of you.  After 1 week he should be sitting quite reliably when you stop and looking at you for a treat.  Don't forget to wait for him to sit all the way before giving the treat.  Do this BEFORE his normal food, I actually feed all my dogs food during training and they never get a normal meal.  Do not say sit, only use the whistle to talk to him.

This training accomplishes the following

• Whistle means sit
• Sit means yummy food
• Dog loves to sit as a result
• Dog learns to automatically sit when you stop walking
• Your heeling becomes better because his attention is on you, waiting for you to stop

Platform Training for Sit

Now place your dog on the top of a small platform. Blow the whistle for sit and treat.  Even if he is already sitting, give a treat.  Now walk around behind him and blow the whistle and pull on his leash at the same time to make him turn around and face you.  When he turns, even a little, click and treat.  Keep doing this until he turning the entire way and then sitting.  Eventually he won't sit still and will try to face you at all times and you might need to hold him as you walk around him.  Sit, Whistle, Spin, Sit, Click, Treat.  During this he is always on leash, and you are always close to him.  Once he is spinning fast, you now need to teach him to stay put when you walk around him and when you are behind him, walk back 3-4 steps, give the whistle, when he turns, click, big praise, and treat.  Keep doing this until you can move back a long distance and walk around him at any point, blow the whistle and he turns and faces you.  If your dog is lethargic in turning towards you, a few sharp leash corrections each time you blow the whistle should motivate him more to turn towards you.  Do this every day, for at least 2 weeks once a day, more often is better.  Using both hands in front of, motion for him to sit squarely, when you turn, pull on the leash.  When he is square, click, run in and treat.

This training accomplishes several things.  

• Dog learns to stay in one position when sitting
• Dog learns to turn and face you squarely
• He learns to sit when you and the whistle command are at distance
• Dog loves the game because he gets wonderful treats as a reward
• This is 90% positive training and all dogs perform best when the work is fun

Platform Training for Handl

• Place your dog in front of the platform and give the command Hup.  Right when he gets up on the platform, give the whistle sit command.  He should turn, face you, and you click and treat.  If he doesn't turn, help him with the leash.
• Extend your distance from the platform by 2-3 steps and motion for him to go to the platform, when he is close, say Hup.  When you can get him to go to the platform from a distance of 5 steps back, start using the command Back before you motion with your body.  Slowly stop using your body and only say Back.  Slowly stop any hand signals and only heel in the direction of the platform and say Back. As he gets better and better at this, extend your distance further and further.  Always you are still clicking and treating when he turns and faces you.
• Now you are ready to start replacing the food with a dummy.  Now instead of running in with the food, Throw a bumper behind him to the right and send him back to get it.