You can't do it directly. Although Explorer shows your mobile device as being accessible from ‘My Computer’, in reality it is using ActiveSync to get at it. Without ActiveSync installed there is no 'Mobile Device' visible.
From a command line there is no direct method to get to your device, but you can do it indirectly in a two-step process.
Firstly, download and install the Windows Mobile Developer Power Tools - WindowsMobilePowerToys.msi from here
One of the utilities in the above is CECopy. It runs as a command line program using “DEV:” to represent your mobile device. The two steps now become:-
1.) Save your spread sheet to the hard disk as C:\TEST.XLS for example, then use:-
2.) CECOPY C:\TEST.XLS DEV:\Storage Card\TEST.XLS
It should do the trick, I have just tested it on WinMo 6.1 and it works a treat! It goes without saying that ActiveSync must be installed on the PC and the mobile device connected. Good Luck!
C:\PROGRA~1\WI1C69~1\CECopy>cecopy readme.txt dev:\readme.txt
Syncing from <readme.txt> to <dev:\readme.txt>
"readme.txt" Copying (New) ... 2/2 k ok