How to add users/group to Local Administrator Group on domain workstations.
You can achieve the same by restricted group policy or set a startup script in group policy
1.Set a startup script in group policy with the following line:
NET localgroup Administrators /add “domain_namedomain_group
That’s it….the next time the computers are started, the group will be added to the local admin group.
Instead of group you can also mention userid as below
NET localgroup Administrators /add “domain_namedomain_Userid”
2.If you want to configure restricted group refer this link:http://www.windowsecurity.com/articles/Using-Restricted-Groups.html