You have to setup the SAN and make sure the Veritas Server is zoned to see the VOLUME your talking about. This would be outiside backup exec.So as long as you can get the array to show as as a local drive letter to the OS on the Veritas Server then ...
Have a look at the c:\winnt\bkupexec.log file on that machine.Search for the key word "return value 3" This will lead you to the error why the remote agent install is rolling back. Most likely something is unsing NDMP port 10000