Eagle: use device in schematic, but hide it on board
That is not the easiest thing to do in Eagle, because it keeps tight relations between symbols and footprints. Adding a variant with blank footprint is not allowed, as the footprint has to have at least as many pads as there are symbol pins.

It is therefore necessary to duplicate symbol (select all-copy-create new-paste), replacing all its pins with lines and then creating new device from this symbol and blank footprint.