Use heat beads to make 2 rows wide around the bottom of the grill and 1 row on top of the bottom row. This method can expect to have a fairly constant temperature ranging from 225f up to about 300f depending on how the vents are setup. The length of this snake changes the time of the burn and can get around a 10-16hrs out of of this method, shorten or lengthen the snake adjusts your times needed but a longer than needed time will prevent burning out mid cook and can always be snuff it out and re-use any unused beads.
Adding chips or chunks of smoking wood around the snakes edge allowing it to burn as the snake burns it's way around will provide the required smoke.
To light the snake ignite 5-10 heat beads in a chimney starter, once fully ashed over place the lit beads at one end of the beads and place a wood chunk on top of the lit beads to start the smoke straight away. Make sure the lit beads are covering the start of the un-lit beads/snake so it will continue to light them and burn it's way around. Place a aluminium tray in the centre of the snake and add water to keep moisture in the grill throughout the cook and also to catches drippings from the meat for an easy clean.