I looked at the @ option too but that seems to require a symbol pin for each connected pad. The example I have is a battery holder, so obviously I want a standard 2 pin battery symbol for the circuit...
I think you call the one on the symbol GND, but it will want all of the GND@X pins connected on the PCB.
You don't have
to connect all of the pins to the device, so you can have GND, GND2, and + pins on the package, but only have GND and + on the device. This would leave you with a permanently isolated pad on the board (so you have mechanical mounting) but no electrical connection.
For example, here's a coin cell battery holder from the Sparkfun eagle library that has a large SMT pad for one side of the battery and two through-holes which are electrically connected on the battery holder, but only one of them is connected in the library device and the results is the electrically isolated through-hole.
Is that what you're after?