Prepare the barbecue for indirect cooking over medium heat (190°C to 230°C).
With a sharp knife, cut the rind around the outside of the ham, around the hock (about 10cm from the end) and straight down the centre. This will help to remove the skin later. Ensure that you have cut right through the rind to the fat, but not into the flesh.
Roast the ham over indirect medium heat for 45 minutes, or until the skin is starting to separate at the centre.
Make the glaze while the ham is cooking. To make the glaze, place all the glaze ingredients into a medium saucepan. Cook the glaze on the side burner or stove top over a high heat until just boiling. Then reduce the heat to low and simmer for 10 minutes making sure to stir the glaze every few minutes to prevent the bottom from burning. Remove the glaze from the heat and set aside until needed.
Remove the skin with tongs. Score the fat in a diamond pattern, being careful not to cut into the flesh, as the ham flesh will dry out.
Decorate the ham with the pineapple rings and glazed cherries, securing with toothpicks.
Liberally apply a layer of the glaze over the ham. Continue to cook the ham for a further 45 minutes, basting every 15 minutes, or until the internal temperature has reached 57°C. The internal temperature will continue to rise 3°C to 6°C while resting (final reheating temperature for cooked ham is 60°C).
Once the ham has cooked, leave to rest for 15 minutes before carving.