First you need an Incidence meter. Measure the current incidence, should be zero on both wings.
I simply elongated both dowel pin holes (per wing panel) with a rat tail file until I acheived 0.5 deg+. Once I had the correct incidence I bonded some 1/16 lite ply doughnuts around the dowel pins to fix the position. Since the wing no longer slides into the 1/16" cutout in the fuse, I elongated the 4mm hole in the wing hold down stub. That's it. It took about an hour to do, no biggie.

After reading Bryan Herbert's thoughts on trimming a pattern plane, I think getting incidence and the CG right for your type of flying is very important.