The Kipping Process Vids above are very good but its been a while since I watched them, so please forgive any repetition here:
With my 'Pre-teamers' I do:
A lot of dish/bent leg dish work lying on the floor, holding lightweight plastic bars by their thighs (This includes static holds and rocking)
Hook a theraband over the low bar and have the gymnast hold both ends, standing up facing away from the bar, then have them pull both ends of the band down to their thighs with straight arms. As they become better at this, they can try it kneeling up and then kneeling down. You can also increase resistance harder by using a thicker band.
Stemme Raises from 2 feet
Stemme Raises from 1 foot, other leg mimics kip action by pushing up the bar.
Pike Leg Lifts hanging on the high bar
Angled leg lifts lying on a block, holding onto low bar
Lie on a coaching block (about 60cm high) holding a lightweight plastic bar above head. Lift feet to touch toes on bar and then at the same time as rolling forwards to stand up, pull the bar right down legs to thighs. End position should be stood up, slightly 'dished' With bar by thighs.
Hang in pike with feet touching the bar. Have gymnast push their feet above the bar as high as they can and back down again. Get them to repeat this as many times as they can without dropping feet.
Think thats all I do - Its all I can remember anyway!
Oh Yes, and have lots of patience and expect to have to remind the gymnasts what to do all the time if they are young!
Good Luck!