In small bowl, dissolve jello in boiling water. 

Mix in lemon juice and juice from the can of pineapple.
Chill slightly (~ 5 mins, while you're mixing the rest of the ingredients).

In separate (larger) bowl, fold together: drained crushed pineapple, cheese, cool whip, coconut, and rum.
Add dissolved jello.

Pour into 1-1/2 qt. jello mold (bundt pan or other same-sized bowl will work fine, too).
Chill until firm.

You wouldn't think cheese would be part of such a recipe, but it adds a nice texture.  This is absolutely delicous, and always a hit at dinner parties.

Send me PM if you have any questions about this recipe.  -Deb