Though nothing beats a mesquite fire, gas grilling is still better than indoor stovetop cooking. I do have a gas grill (weber Q) and love it. Gas is all that is permitted on my second floor apt balcony, though I am moving into a house next month. Do you have any more specific tips about the hickory chips in a tray? I'd like to give it a try.
You can use mesquite or hickory chips with a gas grill real easy. You soak 'em in water for about a half hour, then place them in a double-wrap of foil. Poke some holes in the foil pack and place it under the grill, on top of the lava rocks.
You might need to let the grill warm up for longer than usual to get the smoke coming out real good. Mesquite makes excellent burgers and steaks.
SD
All I do is soak the chips and put them in a disposible tin bread tray (I use two of them) directly over the flame. The boston butts are not over the flame. You want to work it out to where its staggered as to when you have to replenish you chips.
I smoke all kinds of things like this on my gas grill although it can be pretty troublesome for faster cooking meats.