How would I cook mussels on a BBQ?

[trisho.]

Hey gang,

I'm having a rooftop bbq party later on tonight and I bought some mussels for the event. I was planning to cook them in one of those foil pans. Throw in some butter, garlic and what else to call it a day? Should I use water or chicken broth? Wait, scratch the chicken broth...some folks may not eat stuff from the land. Oh! White wine? How long do they normally take on the grill, about 15 minutes or so?

Thanks y'all.