You troll them just like you would during the summer. The fish are smaller of course, a 25 pounder is usually a money fish in the 1 day Derby they have in Homer around St. Patty day usually.
We fish the bluffs north of the spit and continue north both above and below the 1 fish, 2 fish limit line. Bring lots of warm clothes even if you're on a ig charter boat because the strike comes fst and they'll spit the hook if you're not right there attending your gear.
If you're out in a smaller boat like the 18'-24' river boat crowd pay plenty of attention to the weather, if it's coming down the inlet your better off staying in the harbor. Icy decks, frozen fingers, iced up gear, it's all lots of fun. The best fishing happens well before the derby though. Late January and all through Febuary are better fishing than March but they'd never get enough people willing to spend a day on the water if they held the derby in late January.
I like using the same large "tee spoon" spinners that the commerical troll fishermen use. Regular squid hoochies and flashers work well. find yourself 60'-100' feet of water off the beach and troll different depths until you find some fish, I stick to about 35' depth until somebody catches one really deep or real shallow then adjust.
Good luck, it's an expensive way to get kings. hundres of dollars per pound of fish caught.