How the change the access properties odf a USB device

Hi,

I am trying to Implement one function that is like

ChangePartitionAccess(DriveLetter) - switch USB partition to read-only or read-write

i am passing the drive letter of the usb device partition to this method
and it should change the access of the device partition to read only if it is in read - wirte mode
and it should change the access to read - write mode if it is in read only mode.

i would like to know which api i have to use to achieve this functionality

i am using visual studio 2005.

Thanks in Advance