Place the spiral ham in a large roasting pan.  Preheat the oven to 325 degrees.  Score the ham with a knife, creating criss-cross cuts into the ham. Spike the ham with 4-5 cloves. 

Mix together the pineapple juice and ginger ale and pour 1/2 of it over the ham.  Pat the brown sugar on the ham, pressing to crust the brown sugar onto the ham. Place in the oven and bake for approximately 12-15 minutes per pound.  While the ham is cooking, continue to baste it with the remainder of the juices in the bottom of the pan.

When the ham is almost done baking, make the glaze.  Pour the pineapple juice and ginger ale into a medium bowl and microwave for about 45 seconds.  In a medium saucepan, melt the butter and mix with the flour to make a roux.  Slowly stir the juice mixture into the roux, whisking briskly to stir out the lumps. 

Turn the heat up to medium-high.  Stir in the brown sugar and crush pineapple and heat to boiling.  Allow it to boil 3-4 minutes until the mixture starts to thicken, stirring constantly.  Turn to low and simmer for about five minutes until thickened.  Although it is called a glaze, it is more like gravy that you can drizzle on the ham and mashed potatoes. Yum!