Unfortunately, the BIG-IP stores PoolMember by it's address and port. You can configure user friendly names at the Node Address level but that is just a convenience feature in the GUI and is displayed in the Pool Member statistics/state pages. There currently is no way to configure a pool member other than by it's IP Address and port. This is true in the GUI as well as iControl.
The bottom line on features requests like this is: If you can do it in the GUI, then odds are you can with iControl. But, on the other hand, if you can't do it in the GUI, it's a very good chance you can't in iControl as well...
-Joe