NTFS formatted removable storage, safely remove / unmount via command line?

This looks like a tool that may be useful. I haven't used it, but it looks like what you may want. Here is a howto.

The DevCon utility is a command-line utility that acts as an alternative to Device Manager. Using DevCon, you can enable, disable, restart, update, remove, and query individual devices or groups of devices. DevCon also provides information that is relevant to the driver developer and is not available in Device Manager.