Here is a video of personal play with a physical, interactive dog - she has strong opposition reflex and likes "hands on" play. This video shows my dog Cisu playing with me; we play a ton in the ring between exercises. The only thing in this video that I would not do in the ring is push her with my knees or stop moving. Always move to your next exercise as you play, unless the judge in not ready for you.
Note that Cisu always comes to me; I do not pull, prod, grab, or restrain to keep her attention. If it is painful or irritating to the dog, it is not play - it's a person being annoying. To use these skills in the ring, make sure you keep your body relaxed with your hands open, high and visible, so the judge can see that you are not grabbing your dog. You may need to tone it down depending on your dog's behavior. Before you try playing in the ring, videotape yourself with your dog so can gauge the appearance of your play. Never never never grab your dog's ruff or collar in the ring, no matter how much fun your dog might find that interaction.
I teach my dogs that open hands are an invitation to play. To encourage a jump up, my hands are held high. To encourage movement, I move the dog from my left to my right side, simply by varying which hand is available and changing my body postion. To encourage the dog to push back at me, I place my open hands against the sides of their muzzle or neck. If I need the dog to be quiet and contained, I hold my hand close to my side with my palm facing me - my dogs are trained to come into that space between my hand and my body, but they don't' have to heel. They can jump if they wish. Sometimes I pull Cisu in close to my body so I can pet or hug her, but most of the time I encourage her to move around so she can release any nervous energy that has built up during work.
Cisu is always either working or playing; there is no dead time. This is how we trial - 100% structure. Play is highly interactive and fun for the dog, but it is still focused and structured.
When training the beginnings of interactive play, remember to always move away from your dog. If your dog turns away from you, your job is not to follow but to back away. Most dogs will turn back when you do this and you can praise, cheer, and offer another opporunity to interact. If your dog is prone to running around when excited, you'll have to keep this sort of play toned down and highly structured. Try teaching in a small space so "zooming" is not an option. Feel free to use food in the beginning to keep your dog close, unless your dog begins to focus on the food - then practice short bits of play simply for the fun of the interaction.
Here's a video of Ali in his first play session. For those who are interested, Ali is the grandson of Cisu, the dog shown above. He is also Lyra's sire. http://www.youtube.com/watch?v=wTWHQoUnvtg