Yes. You can use 'crazy' in a positive way. I believe its use is more idiomatic, but it is used in this capacity. For your example, you would say, "I am crazy for ice cream.". It means that you are very fond of ice cream. To say, "I am crazy for eating ice cream" would make someone think that your eating the ice cream is not a good thing, and people would question why you would do something bad to yourself.

To add to Kim's answer, you can also be "crazy for" or "crazy about" a person - madly in love with them. There are famous pop songs with the title "Crazy for you" and "Crazy about you".