I'm a former IT guy and I'll take a swing at this. The WDTV Live is really designed for home so it doesn't really have a way to find a share on another subnet. There is no way to enter an IP address manually for the target share. But as long as you are on the same subnet as the server it should see a network share on the server with the music on it. But not knowing anything about your server I can't guaranty it. Not very helpful I know but I have no way of knowing how your network is configured.
If you're on different subnets then your only low budget choices are simple - an external drive hanging off the WD, add a drive to a PC that's on all the time and share it on the network, or setup a local network attached storage device.
Now for the legal disclaimer - I AM NOT A LAWYER. But as a former IT manager I can tell you that there are legal booby traps where you are going. You may not have any problems but disgruntled employees have reported employers for allowing the sharing of ripped music across their networks and companies have been sued. Those suits get people fired. In my LAYMAN's opinion there may be less legal risk to the company if you store legally obtained music on an external drive attached to the WD. Take my opinions for what they are worth (not much) and consult your own legal experts. Also be aware that youy company's IT guy may (probably will) come looking for your scalp for adding anything to the network.