Shared Folders Options : Map folders to drive letters

In Parallels 5, how is it possible to ensure that the same drive letter is always used for a mac shared folder?
For instant I want my Mac partition DATA to always be mapped to X: in Win7.

This is important as my Win7 apps such as Outlook 2010 stores the paths for mail accounts in the registry.

Also, I noticed that in Parallels 4 there used to be an option called "Map folder to drive letters"
See user guide page 168 Shared Folders Options
http://www.parallels.com/ca/download/file/doc/Parallels_Desktop_for_Mac_User_Guide.pdf

That option is not in Parallels 5
See user guide page 180 Shared Folders Options
http://download.parallels.com/desktop/v5/docs/en/Parallels_Desktop_Users_Guide.pdf

Thanks
JM

 

No one?

No answers on this?

Should I then assume that it's not possible to control the drive letters that are mapped?