Company-wide Desktop Picture on Mavericks Clients

Question

We're looking at rolling out Mavericks on our systems at work, and I have set up a test machine to make sure everything will work as expected. We have a Lion server that is using Workgroup Manager MCX (instead of Profile Manager, which will change) to distribute policies to all the workstations. All of them are working well except for the desktop picture.
Now, I understand that the setting for desktop picture in Mavericks is no longer in a plist, but in an sqlite database. Is there any way to set the desktop picture using the Workgroup or Profile Managers for a Mavericks client? I don't want to replace the default picture on Mavericks systems because we update the desktop picture regularly.
EDIT: I should add, I tried to write a login script to do it, but I couldn't get it to run. The script has this single line:
tell application "System Events" to set picture of every desktop to "/Volumes/Groups/Everyone/Wallpapers/Current.png"

Answer 1

Your script is a kludgy hack that won't prevent users from changing the Desktop for the entirety of their session .
The correct way to do this is with Managed Preferences for OSX also called 'MCX' as you have already seen.
There is a tweak that should still work on 10.9 to import all the Apple based 'managed preference keys'.
Get Workgroup Manager for the same OS as the server (you may need the server admin tools, it varies, search for both). It may need to be the 10.9 version on Mavericks.
http://support.apple.com/downloads/#workgroup%20manager
Open WGM on a client, connect to the server (do not work in the local node!). Select the group or computer group you are managing & select the 'Preferences > Details tab'. Click the + button to add the following…
/System/Library/CoreServices/ManagedClient.app
This will give you the power to manage a lot of extra keys, find the 'Desktop picture' in the list, double click it, decide how often to manage it (once = first login, often = at each login, always = what it says ).
Select 'Often' & create a New Key, click the new item & select the key to manage (in this case Background). It should autofill the other values (e.g. image path & the path to the current Desktop. Sometimes Always won't create the key correctly, so create it inside often & drag it down.
Once all that is saved login as a member of the managed group & it should pull down the desired MCX prefs (reboot).
Your Macs will need to bound to the server for this to work & I haven't tested on 10.9 (WGM doesn't want to apply these to the local node, which may indicate it isn't possible.
I'd strongly suggest you copy the desired image to the Macs in question to increase reliability, or host it in an auto mount that appears in /Networks.
Good luck