This is not possible...
When you have formatted a CDRW it looses a lot of capacity, only 530 MB left I believe. You can however burn a CDRW as a regular CD and then it should be capable of storing 650 MB.
I don't know if there are High Capacity CD-RWs (as there are 80, 90 and 99 min CDRs), but that could be a solution.
If you have 648 MB of normal data, you might use WinZip or WinRar to compress the data so it becomes less and might fit on a formatted CD-RW, but I don't believe there are compression tools such as you describe above.