I've done it on my gasser using a small cookie sheet and wood chips instead of chunks. Place the cookie sheet directly on top of the burners(under the actual cooking grates) sprinkle some chips on and smoke away. The chips will smolder after a bit and the cookie sheet acts as a diffuser so you get a nice indirect cook. Good luck.
UDS, Akorn, Weber Red Head Kettle, Drum Grill, Gasser w/cobwebs all over it. I'm JD.