Did you try this? I'm doing one tomorrow for my dad. My son raises lambs and I butchered one this week and cut and wrapped for my dad. Figured I'd do a Greek marinade/rub on it and put in on the grill.
I love lamb but have never tried it in the smoker. Will have to pick one up and give it a whirl. I would think a mild, maybe fruit wood smoke would go good. haven't looked but would bet there is some YouTube info out there. Good luck