Sadly the only way to eject a cd drive(or zip drive) I know of from the command line is by using one of the many freeware utilities programs from the web. There are great command line tools to eject a tape from a tape drive built into most modern version of windows but not cd eject. So to remotly eject the cd the target would need software installed on it to preform that function.
And unless the user makes chanegs for themselves or the administration, by default Net Send is blocked. Some system admins use it so it may be enabled on some networks.
QUOTE(http://www.michna.com/kb/WxSP2.htm)
NET SEND messages no longer received
First enable the File and Printer Sharing exception in the firewall.
Service Pack 2 also disables the Messenger service.
Go to Control Panel, Admin Tools, Services, double-click on the Messenger service, set its start type to Automatic, so it gets started automatically the next time you boot, and also start it immediately if you want it right now in your current session already.