Teradata BAR with Netbackup

Hi

I am using Netbackup with TeradataBAR Solution.

we use Netbackup for schedules and catalogue management

Netbackup will trigger Teradata BAR script from netbackup Policy, we have a requirement 

Before backup initiation and after backup completion we wanted to run some pre and post scripts which will release locks for tera data tables.

can some suggest how can i implement these pre and post scripts...which helps me a lot....

Thanks in advance...