Yeah, the machines do not need to be DCs directly. If the locations have a PC with a server OS say Windows Server 2003, that would work too. Mainly, it's the connection limit that is the issue. Any PC can be used to push out the install packages. If you are using a Windows XP/Vista/7 based client, you only get 10 concurrent connections.
So, copy the Push Deployment Wizard files found here on the SEP (Symantec_Endpoint_Protection_11.0.6_MP1_Xplat_en.dvd.zip) install zip file:
Tools>Push Deployment Wizard
From there copy the install packages over to the PC at the location, and run clientremote.exe.
Also, I have heard some (maybe next release) rumblings around the forum that Symantec is going to include the ability to update client packages from the GUPs. This would greatly help. I thought it was supposed to be included in RU6, but it wasn't. Disappointment. :)
Mike