A few years back, Rick Graybill wrote a booklet on fishing Lake Chelan that had tons of good information in it. I got mine at Hooked On Toys in Wenatchee. If it's still available it's a gold mine of detail on how to run downriggers super-deep and on where to fish. It's mainly written for chinook (which as mentioned earlier are just about gone) but it has plenty to get you going on macks too.

You'll want super heavy downrigger balls for this fishery-- I got 15-pounders at Hooked On Toys.