Appsync postmount script

We are using AppSync service plan to perform db2 copyback (using filesystem repurpose ). It seems like postmount script needs to be run as appsync user. we are trying to do chown command as part of postmount script, but unfortunately appsync user doesn't have the privilege to run chown. Is there anyway to run postmount script to run as root (without having to put the root username/password). This is similar to call out script which is always run as root.

Thanks,

Vijay Govindan