For the cakes-Prepare three round 9″ pans by lining the bottoms of each with 9″ circles of wax paper. Grease the wax paper with Crisco Spray and then sprinkle with flour. Mix the cake mix, lime jello, oil, eggs, orange juice and water together for 2 to 3 minutes at medium speed. Pour an equal amount of the batter into each of the three lined cake pans. Bake at 350 degrees for 25 minutes.
For the glaze-
While the cakes are baking, knead two key limes against a hard surface to loosen the juice inside of them.
Cut each of the key limes in half. Squeeze 1/4 cup of fresh key lime juice into a small bowl. Pour 1/4 cup of bottled lime juice into the bowl of fresh lime juice. Mix in 4 tbsp. of confectioners sugar.
When the cakes come of out the oven, and while they’re still warm, use a spoon to drizzle the glaze mixture onto the entire surface of each of them.
For the icing-
Mix the margarine and cream cheese together. Mix in the remainder of the box of confectioners sugar.
Add the vanilla, and mix until it’s smooth. Remove the first cake from its pan, discard the waxpaper on the bottom of it, and spread a layer of icing on the top of it. Remove and stack the second (wax paperless) cake on top of the first one, and spread a layer of icing on the top of it. Remove and stack the third (wax paperless) cake on top of the second one, and spread a layer of icing on the top of it. Use the remaining icing to cover the sides of the cake.
Refrigerate cake until ready to serve.