Hi Nick. Without knowing a little better about what it is you're trying to accomplish, it's a little difficult to say how (or even if) it can be done.
You mentioned creating a matrix between test cases and requirements, but what information would the checkmark denote? Test cases can only be owned by exactly one use case or requirement, so I'm not sure how helpful a matrix view would be. Are you trying to show some sort of relationship between use cases and requirements, test cases and requirements, or something else?