Preheat oven to 180C/160C fan-forced.
Place pineapple juice, ginger beer, sugar and mustard in a medium saucepan over medium-high heat. Bring to the boil. Reduce heat to medium. Simmer for 20 to 25 minutes or until slightly thickened. Remove from heat. Stand for 10 minutes.
Meanwhile, using a small sharp knife, cut through ham rind about 8cm from shank. Starting at the opposite end to shank, run your thumb under rind to separate it from fat. Peel back and remove rind. Score fat at 1cm intervals. Wrap shank end in foil.
Place ham on a lightly greased wire rack in a large roasting pan. Add enough boiling water to pan until it reaches 2cm up sides of pan. Brush ham with 1/4 of the pineapple glaze. Bake, basting with remaining pineapple glaze every 20 minutes, for 1 hour 30 minutes or until ham is golden and caramelised. Remove and discard foil from shank. Serve.