Using the force_push attribute
When assigned a value of yes, the force_push attribute tells NIM that the target of the bos_inst operation does not necessarily have the bos.sysmgt.nim.client fileset installed and configured.
NIM will attempt to NFS mount or copy the minimal client support to the target system to perform an unattended installation or migration of the base operating system. If client support is copied to the target machine, NIM will automatically expand the necessary file systems on the target unless the auto_expand attribute to bos_inst is set to no.
The force_push attribute requires that the client grant root rsh permissions to the master and that the key on the client be in the normal position. The force_push attribute also requires that a bosinst_data file be allocated to the target machine to indicate that a no-prompt installation should occur. The force_push attribute is set to yes by setting the Force Unattended Installation Enablement? option to yes when using SMIT to perform the bos_inst operation.