Thanks Delphix team. got the solution.
----. If no pre/post scripts are required then-----
attachSource *> edit source.operations.preSync'dSourcename' attachSource source.operations.preSync *> add
'dSourcename' attachSource source.operations.preSync 0 *> get
type: RunCommandOnSourceOperation (*)
command: (required)
'dSourcename' attachSource source.operations.preSync 0 *> set command=#
'dSourcename' attachSource source.operations.preSync 0 *> back
'dSourcename' attachSource source.operations.preSync *> back
'dSourcename' attachSource *> edit source.operations.postSync
'dSourcename' attachSource source.operations.postSync *> add
'dSourcename' attachSource source.operations.postSync 0 *> get
type: RunCommandOnSourceOperation (*)
command: (required)
'dSourcename' attachSource source.operations.postSync 0 *> set command=#
'dSourcename' attachSource source.operations.postSync 0 *> back
'dSourcename' attachSource source.operations.postSync *> back