Silence of the Leg O' Lamb marinade?

I'd just put the paste on and leave it in the fridge overnight, maybe in a large sealed plastic bag. Treat it like a dry marinade or rub. When you roast it the juices from the lamb should combine to make a nice sauce. . Also,this may not work on your stove, but you can buy grill racks that help your stove function like a grill.