There are a couple ways to do this with CMS. The 'cheater' way would be to create a software resource for the xml file, and then have the install command (I'm not sure where the file needs to be installed, so f be something like:
cp SyLink.xml /Library/Application\ Support/Symantec/SMC/SyLink.xml
The other option would to mount a network share where the file is located, and then copy it from the network location to the local computer. Something like:
#!/bin/sh
Server="<server fqdn>"
SharedFolder="<Share Name on Server>"
UserName="<username>"
Pass="<password>"
#Note that if your password contains special characters, you'll need to use their asci value replacement
mount -t smbfs //$UserName:$Pass@$Server/$SharedFolder /Volumes/$SharedFolder
#Having Spaces in the share name may also be an issue
cp /Volumes/$SharedFolder/SyLink.xml /Library/Application\ Support/Symantec/SMC/SyLink.xml
Let me know if either of these work, or if you would like any clarification.