Howdy, Space Ranger!
I'd recommend checking out the following documentation to get filesharing going without interrupting a current user.
Apple Remote Desktop Administrator’s Guide
http://images.apple.com/remotedesktop/pdf/ARD3_AdminGuide.pdf
Page 145:
Executing a Single UNIX Command
Using the UNIX Command window, you can send a single command to the selected
client computers. The command is executed using the bash shell.
To execute a single UNIX command:
1 Select a computer list in the Remote Desktop window.
2 Select one or more computers in the selected computer list.
3 Choose Manage > Send UNIX Command.
4 Type or paste the command.
If your command is a multi-line script, enter each command on its own line. If you want
to break up a single-line command for better readability, use a backslash (\) to begin a
new line.
5 Set the permissions used to execute the command.
You can choose the currently logged-in user, or choose the name of another user on
the client computers.
6 Click Send.
For information regarding Terminal commands that can be useful (this is for 10.3 and later, but the relevant command does work in 10.8):
Mac OS X Server Command-Line Administration
http://manuals.info.apple.com/en_US/MacOSXSrvr10.3_CommandLineAdminGuide.pdf
Page 65:
Commands you can use to create share points and manage AFP, NFS, Windows (SMB), and FTP services in Mac OS X Server.
Share Points
You can use the sharing tool to list, create, and modify share points.
Best regards,
Allen