the link to how to have your computer recognize your Sony as a drive instead of music device.
One precaution, this does not make the Sony into a MSC device. It causes the computer that it's done on to install the MSC driver for the player. If you connect to another MTP enabled computer it will still recognize the player as an MTP device. If you add files or folders on that computer the rebellion starts again.
However that doesn't stop the "home" computer from continuing to see the player as a drive. When you reconnect there it will still be seen as a drive letter.