It can be done via the command line. Open up a Command Prompt (Press the Windows Button and type CMD or navigate to All Programs -> Accessories -> Command Prompt). Then you just need to use the command below that matches your OS. For 32 bit Windows: cscript "C:\Program Files\Microsoft Office\Office15\OSPP.VBS" /inpkey:yourkeygoeshere For 64 bit Windows (assuming you are using 32 bit Office): cscript "C:\Program Files (x86)\Microsoft Office\Office15\OSPP.VBS" /inpkey:yourkeygoeshere Obviously, you need to replace yourkeygoeshere with your product key. Note: If you are installing a 64 bit version of Office on 64 bit Windows, the command for 32 bit Windows should be used (or just delete the (x86) part since it won't be installing to the C:\Program Files (x86)\ directory).
You can configure a Group Policy Object (GPO) that gets applied to the desired user accounts to do this. In Group Policy Editor (GPE), navigate to User Configuration\Windows Settings\Administrative Templates\Desktop\ Active Desktop and enable Active Desktop Wallpaper. In the Properties dialog box of this policy, you specify the full pathname of a .jpg, .bmp, or .html file and select whether to centre, stretch, or tile the image. For this policy to work, you must also Enable Active Desktop, which you'll find in the same policy folder.
+ANTIALIAS Toggles antialiasing on 3d models. +ATM Gives you 1000 metal and energy. +BIGBROTHER Scrolls through your units. +BPS Shows data transfer rate in a multiplayer game. +CDSTART Starts the CD music. +CDSTOP Stops the CD Music. +CLOCK In-game clock addition. +COMBUSTION Kill all other players' units. +COMPRESSIONTURNS Multiplayer compression on / off.. +CONTOUR# Displays a 3D contour, # = 1-15. +CONTROL# Control a different skirmish AI. +DITHER Dithering instead of line-of-site. +DOUBLESHOT All weapons do twice the damage. +FSHADOW Takes away feature shadows. +GAMMA # Changes screem gamma (0-20). +HALFSHOT All weapons do half the damage. +HONK Makes units honk when they stop. +ILOSE Causes you to lose. +INFARED Toggles fog of war on / off. +IWIN Causes you to win. +KILL# Kills off a player, where # is 0-4 . +KILL Kills all units (including yours). +LIGHT Hide the shaded object (?). +LOGO Change your color (not tested in multiplayer). +LOS # Toggles line of sight settings. +LUSHEE Limited resource increase. +MAKEPOSTER Makes a huge BMP file of the current map. +MAPPING Covers the screen with darkness. +METEOR Causes a random meteor shower. +MUSICMODE # Changes type of CD music being played. +NANOLATHING Nanolathing 2X but also -2X metal usage. +NETSTATS Makes BPS counter go mad, then go normal. +NOENERGY Drops your energy to 0. +NOMETAL Drops your metal to 0. +NOSHAKE Toggles antialiasing on 3d models. +NOWISEE Full map, no LOS. +RADAR 100% radar coverage. +RELOADAIPROFILES Reloads the AI. +SCREENCHAT Enable/disable chat text in multiplayer. +SETI Toggle minimap on / off. +SETSHAREENERGY # Shares energy while keeping # amount for yourself. +SETSHAREMETAL # Shares metal while keeping # amount for yourself. +SFX Enable/disable sound effects. +SHADOW Removes shadow from buildings. +SHAREENERGY Shares energy with your allies. +SHAREMAPPING Shares map info with your allies. +SHAREMETAL Share metal with your allies. +SHOOTALL Makes your units fire at everything the enemy has. +SING Makes units sing when ordered. +SWITCHALT Switch squads with # keys only. +TILT Max out men and material (?) +TSHADOW Takes away shadowing on units. +VIEW# 100% radar coverage. +ZIPPER 100% radar coverage.