Set drive letter for partitioned drive

I have Win ME, not that I think it matters form Win 98. I have a 40gb HD on the primary master, in two 20gb partitions. Fine…there had the C: and D: letters. Then I added a 6gb HD on the primary slave, but it took over the D: drive letter, making my 40gb letters C: and E:….how can I set these, since dvc mgr doesn’t allow this type of manipulation for hard drives?