As I said in my previous post, yes you will still use the Powershell cmdlets to put EV in backup mode. You can either have NBU execute the scripts or use Windows Task Scheduler. I would recommend NBU calling the script as part of the backup job.
Page 13 of the NetBackup 6.x and Enterprise Vault 8 Integration doc has this:
There are many approaches to configuring your pre- and post-backup routines. These options are explained in detail in the companion document available at http://support.veritas.com/docs/312327 . This backup product-agnostic document will guide an administrator through configuring the Powershell cmdlets which can place all or part of the Enterprise Vault 8 environment into backup mode and return it to normal mode after backups.
These cmdlets can be added into pre- and post-backup batchfiles or scripts, and executed from either the NetBackup server or from the Windows Task Scheduler of the Enterprise Vault 8 server.