Both IC Cards and CRC Cards have advantage of simple, easy to understand.
Both IC Cards and CRC Cards are used to describe the object in a system. Essentially, when we think about them, they are very similar in the description power for describing objects.
First, they both has the object name.
Second, both describe what should be done by this object. In IC Cards, it is called "Task". In CRC Cards, the word "Responsibility" is used.
Finally, both can be used to describe the relation among objects. In IC Cards, this can be done through the "message". In CRC Cards, this term is called "collaborators".
Therefore, I think both technique are similar description power for describing object. And it should no difficult to convert form one to the other.