I might be able to update this answer later with more detailed steps, but here's a general overview of what you need to do to get it installed.
- Run the 64-bit LiveMesh setup executable again until you get the error message. Leave this window open.
- There should be an AppData\Local\Microsoft\LiveMesh\Setup directory -- copy of the contents of this folder to another location. (There should be an MSI file at least.)
- Close the LiveMesh setup.
- Install either Orca from the Microsoft Windows SDK (instructions here) or InstEd It! (I haven't used this before, but it should do the job also).
- Open the LiveMesh MSI file in Orca or InstEd It! and edit the LaunchCondition restriction to allow for install in Windows Server (see an example here).
Again, just an overview -- if I get a chance I'll try and put exact info for your specific case. And, of course, note that Microsoft may have a very good reason to not supported on Windows Server, so this is definitely at your own risk.