Hi inquizzitive,
A 660 is a strong first CAT score. To raise this score to 740+ will require some significant work though - you'll have to make improvements to BOTH the Quant and Verbal sections.
After taking each CAT, you should plan to do a FULL review of the CAT (including ALL the questions, not just the ones you got incorrect). You should be looking to define WHY you got questions correct and incorrect. Did you get questions wrong because of silly/little mistakes? Because the questions were too hard? Because you were low on time? The little mistakes are the things that you have to work on first - physically redo questions and practice good note-taking and organization.
In answer to your question, it's tough to say if 5-6 weeks will be enough time for you to make the necessary adjustments and improve. We need a better understanding of the types of questions that you're getting wrong and WHY you're getting them wrong. You will probably also need to invest in some non-book study resources.
GMAT assassins aren't born, they're made,
Rich