Dear tzinger,
To rotate the border of a viewport, you should replace
the border by another object using the VPCLIP command.
To rotate the view inside the viewport, you should set
the system variable WORLDVIEW to 0, set the UCS on
desired direction, and set the view direction using the
VPOINT command. The following code shows you how to do it.
(defun c:RVP()
(setvar "worldview" 0)
(command "ucs" "z" 45)
(command "vpoint" "0,0,1"

)
Regards,
Farzad