Not much to say really, been making them for over a year now, ever since I figured out how to do a meatloaf on a grill it's my preferred way to cook them. Nothing like a meatloaf that was cooked w/ open flame and wood chips.
The toughest part is to heat up the grill without burning the bottom of the meatloaf. Cooking time is a bit longer than a regular oven: 90minutes to 2hours depending on how you provision the heat source. I use a charcoal grill w/ a side smoker attachment, load up the side smoker w/ a bunch of charcoal, and usually add a bit more charcoal about half way through the cook cycle. Also, have to turn the meatloaf a couple of times while cooking (since heat is usually on one side of the grill).
I made 2 3lb meatloafs over the weekend. Largest meatloaf I've cooked was a 6 pounder... that was more of a meatcake... w/ baked potatoes and vegies all at the same time :thumbsup: