I just did a batch of jerky. Used eye of round as it was on sale. Sliced it uniformly WITH the grain, then marinated for a couple days (search for River City Jerky on biggreenegg.com for the recipe.) I then got my grill to about 180 and on it went for 5-6 hours or so with a good amount of hickory smoke. It is VERY tasty, and no preservatives.
I used my ceramic grill for this one, but if I was to use the WSM, I'd go with no water in the pan (sand maybe), and just a few lit briquettes to ensure that you have the utmost control as you creep up on 180.
Good luck!
Rich