Place clams in sink, and cover with cool water. Rinse clams well, rubbing together to dislodge grit, and drain. Repeat until water is clear. Drain clams. Place in a large bowl, and cover clams with cold water. Stir in cornmeal and salt. Refrigerate and soak for 30 minutes.
Preheat grill to medium-high heat.
Remove grill rack; set aside. Pierce the bottom of a disposable aluminum foil pan several times with the tip of a knife. Place pan directly on heat element on bottom of grill; add wood chips to pan. Place grill rack on grill. Arrange clams in a grill-safe roasting pan, large shallow baking pan, or sturdy disposable foil pan. Pour beer and 1 cup warm water over clams; arrange garlic and lemon over clams. Place pan on grill; cover grill, and cook 15 minutes. Stir clams. Cover grill, and cook 5 minutes or until clams open. Discard any unopened shells.
Sustainable Choice: Lobsters & Steamers. Lobsters trapped off waters near the Northeast U.S. and Canada are smart options, as are wild-caught or farmed soft-shell clams.