Of course, you need a whole lamb to get started.  I get my lamb from my friend Cindy at Bellwether Farms (www.bellwetherfarms.com) and pick it up all "dressed" on the day of the party.  The head stays on, of course.  After removing the innards (except for the kidneys) for separate processing, I sprinkle a few tablespoons of herbs and spices  (ras-el-hanout, thyme, rosemary) inside the rib cavity as well as some salt.  Using a sailmaker's needle and some twine, I sew up the belly flaps together so that the melting inside fat will combine with the spices to baste the chest cavity and the ribs.  Next, the animal is impaled on the spit and all four legs are tied to two brackets so that the lamb can be rotated as necessary.  And on to the fire, which has already been started.  I designed the coal bins so that the heat comes from the sides (and the melting fat falls on the ground and won't flame up).  These bins rest on a couple of concrete slabs so that they can be moved closer or further from the animal, for better temperature control.  Mesquite is my fuel of choice, because it burns much hotter than regular charcoal briquettes.
After putting herbs and spices inside, the cavity is sewn shut with twine.	Good to go, and on to the fire...!
It's very important to be patient...  The outside of the lamb must not be allowed to burn or to get brown too quickly.  I start with moderate heat and add more mesquite chunks towards the end of the cooking process to bring the heat up.  The lamb is turned 1/4 turn every 5 to 10 minutes or so (there always are volunteers for that, especially when a nice French dry rosé wine helps staying cool...)  Occasionally I baste the skin with melted, salted butter so that it will become crispy - the mark of a successful mechoui.  Other people also spray salted water on the skin for the same purpose. The entire process takes up to seven hours depending upon the size of the lamb.  There are now so many people clamoring to be invited that I have to use a 40-45 lb. lamb (double the size of my first one...)  which of course takes much longer to cook right.	And it's now ready...! Bon Appétit...!