Hello,
I know that Veritas has a special SharePoint agent, but you should be able to backup your SQL databases without it. I am not even using the SQL agent, I am just using maintenance plans in SQL and then our veritas software does file backups.
For doing site backup I am using the built in stsadm.exe tool (just doing SQL backups is not enough if you want to restore a site). Check the Windows SharePoint Services Administrators guide from Microsoft, there you will have an instruction on how to use the stsadm.exe tool.
Cheers,
Thomas