1. Check out past postings on the Georgetown Lake page of the Montana fishing reports and conditions sub-forum. There's a lot of good information on that page, and that page is the best place to ask for advice about fishing on Georgetown Lake. Click on the little page icon on the right side of the Georgetown Lake row to see the lastest posting; if you click on the Georgetown Lake link, you'll get the very first posting, which will be many years old.
2. You will tend to find kokanee in deeper water than you find trout. Look for water which is 18-20 feet deep.
3. To attract kokanee to your lure, rig a flasher about a foot and a half above your lure. A big silver Pot-o-Gold spoon or a kokanee dodger make a good flasher. Jerk your line up a couple of inches every second or so to flip and flash the flasher until kokanee show up. Then just twitch your line to wiggle the lure - if you continue to flash, you'll tend to jerk your lure away from the kokanee. Another major advantage of using a flasher is that its weight keeps your fishing line tight, and helps you make instant hook sets.
4. Everybody has a different favorite lure, but you can't go wrong with a small red rocker lure baited with a maggot. As I said above, rig it about a foot and a half below your flasher.
5. The best way to catch a lot of kokanee is by sight fishing. Set up a dark ice house over your hole, and watch your lure down the hole. This is feasible a lot of the time on Georgetown Lake because the kokanee are often in the top 8-10 feet where you can see them coming in to nip at your lure. When kokanee come in and nip at the lure, try to set your hook. Timing is critical. You will probably only nail a kokanee about one out of five times, partly because you miss your timing, and partly because many times a kokanee doesn't actually take the lure into its mouth. Another advantage of sight fishing is that it's quite entertaining, because you get to see kokanee milling around your lure and coming in to nip at it.
6. A fish finder is frequently helpful, particularly if the kokanee are down out of sight, because it shows you the depth at which the kokanee are coming through, and lets you jig at that depth even if you can't see the kokes down the hole.
7. When the kokanee are down so deep that you can't see them down your hole, or they are only vague shadows, an underwater camera will let you sight fish for them. Figure out the depth at which the kokes are moving through, set your camera at that depth, and hang your lure in front of the camera. A fish finder will help you get your lure and/or flasher to the same depth as your camera. A camera is also very helpful on very dark days. A couple of days ago we couldn't see fish by looking down our holes because the snow was so deep that the water down our holes looked black, but we could see them just fine on our cameras. I caught 44 kokanee and the guy I was with caught 56. I would have only caught a fraction as many kokes on that day without an underwater camera.
I'll copy this exchange to the Georgetown Lake page of the Montana Fishing Reports and Conditions sub-forum, because that's where most people who are looking for information about fishing on Georgetown Lake will look.