You will probably be dissatisfied with the result. Using Step 3 books takes you too far beyond the scope of Step 2. It will make you a better intern and I hope you learn something from it! However, the people who are successful using Step 3 materials for Step 2 are those people who not only have already been through the Step 2 material, but are also the type of people who can retain massive amounts of knowledge. They need extra stimuli.
If anyone has had a dissimilar experience, please post. I'm willing to bet that success stories with step 3 material are from the people who would have been a success story anyway. It wasnt the Step 3 material that made them, it was the person to begin with.