I kokanee fish here in montana. I am not an expert, but I have come home with half a bucket full many times.
To catch a lot of kokanee you will need a sensitive rod, or a spring bobber. The Kokanee bite is very subtle and if your not paying attention you will miss the bite.
In Mountain lakes here in Montana, I use small jigs, sweedish pimples etc. tipped with maggots or eurolarva(died maggots).
It seems to me that most first time Kokanee fisherman want to hook em like they are bass. Some of you know what i mean. They get a bite, then next thing you know thier rod is through the ice shack roof.
Like trout, kokanee mouths are fragile and your can rip your hook right through their mouths. Instead gently lift your rod tip when you feel a bite, its enough to hook them and you will bring in more fish.
For Kokanee we do better fishing in an ice shed, early in the morning 2:30 am to about 8-9am. Water depth is about 20-40 ft of water. And I usaully start jigging near the bottom and move my way up until i get one.
Move around if you don't catch any.
Since Kokanee ARE plankton eaters putting a neon light down in your hole(while its dark of course) just below the surface will attract the plankton, which in turn attracts the fish. Every time i have used a light, i have had awesome fishing. Plus it never hurts to throw a few maggots down your ice hole every once in a while.
Oh yeah Corn works too. Test out both and see what you do better with.
I hope this works for you in Oregon. Oh yeah one more tip....
If you see any "old timers" fishing on that lake just bring em a couple of beers and causually bs for awhile. You never know what 'secrets' they will reveal. Thats how i learned, that and some testing.