I had the opposite problem. I wanted to STOP Windows from reading (or even mounting) the OS X partition as D:. I found this solution on the Internet. Rename AppleMNT.sys in the System32 folder (in \Windows) to have a different extension, like .sav e.g..
This worked like a charm for me, so maybe you need to look for, or somehow acquire if you don't have it, the AppleMNT file and put it in the System32 folder.