Step-by-step instructions in NetBackup 7.5.0.x for VMware Administrator's Guide: http://www.symantec.com/docs/DOC5605
You will see in this doc that you need a Windows or Linux client or media server to add as Backup Host.
Other helpful Connect content:
(Netbackup) VMWare Backup over SAN
VMware HOWTO
Nuts and Bolts in NetBackup for VMware
Compatibility:
Statement of Support for NetBackup 7.x in a Virtual Environment: http://www.symantec.com/docs/TECH127089
