I know of two ways.
one is to setup and bp end script that after the backup finished it runs this script (but I never used it).
What I have done for things like this is setup a script on the client to do what I want and include in that script the user inited backup (these means you have to have a user schedule in your policy).
this way I can have a script on my system set up in cron that starts and does some stuff
then kicks off the backup to netbackup
then does some more stuff when the backup is done.
like the previous posting,,, if you can script it you can do it.