I'm a folkstyle wrestler who likes to tie up in underhooks. Can I learn to use throws from there?

Sit on the floor with the soles of your feet together. Take hold of your toes with both hands and pull gently toward your forehead. Lean forward as far as you can. Hold for a moment, then go one inch farther. Hold for a few seconds, then sit up and rest a few seconds. Do it again and this time go one half inch farther. Be sure to observe the same holds and rests. Now do it a third time and go one fourth inch farther. Relax for a while and then do something else. You can repeat this exercise as often as you want, but DO NOT TRY TO HURRY IT. It takes three weeks or more to get noticeable results and if you try to hurry it along you will tear a ligament and it will take time to heal and then it will still take three weeks to see results. The result is to go from a stand to a split without tearing your crotch out.

Now get a training partner that you can trust not to blab your secrets. Stand face to face.
1. Pretend to stumble and push your right shoulder against his chest.
2. Put your right foot outside his left foot.
3. Get your right hand on your left side.
4. With your left hand, grab your opponent's wrist.
5. With your right hand, grab your opponent's face or hair or neck.
6. Step to the left. This brings you into a split position, weight on your left foot. Your opponent falls, and his right elbow comes across your knee.
7. Move your right knee to his shoulder and now you can hold this person down for any length of time. You even have your right hand free for all manner of tricks. (Assuming this is high school wrestling, do not hang onto the neck.) If he tries to struggle, move your right hand to his shoulder and raise your weight on your hands.

Using an underhook, the throw is somewhat similar but not as easy. Swing your back leg to get leverage. Go to youtube and search "oni kudaki" to see how it's done.