Looking here I can see extracting a downloaded mpam-fe.exe and copying the files to a shared folder should allow me to run the following command from an MSE client so it will pull down the updates from the share:
MpCmdRun.exe -SignatureUpdate -"\myserver\MSE-Defs"
This does not work. When I run this and check the log (C:\Users\ME\AppData\Local\Temp\MpCmdRun.log) I see:
MpCmdRun: Command Line: "C:\Program Files\Microsoft Security Client\MpCmdRun.exe" -SignatureUpdate -"\\myserver\mse\" Start Time: Fri Sep 27 2013 08:52:07 Start: MpSignatureUpdate() Update started Search Started (MU/WU update) (Path: http://www.microsoft.com)...
So its totally ignoring the switch and going out to http://www.microsoft.com. If I remove the default gateway from this computer's NIC config the update fails.
How do I actually make MSE pull down definitions from a UNC path?
edit: I know I can just run mpam-fe.exe and it will update, but I'm still curious about how to make the unc switch work