
   Is it possible through either pin configuration or through software
   programming to change the IP numbers on an ethernet card?

The Ethernet card doesn't use the IP number (32-bits, usually
#.#.#.#); it uses the Ethernet address (48-bits, usually
#:#:#:#:#:#). I have never run across an Ethernet controller that
cannot be programmed to use an address that is not assigned to it.
DECNET requires this feature.

However, that said, there is no reason to ever change the Ethernet
address.  They are globally unique, the first three bytes being
assigned to the manufacturer by the IEEE, and the last three by the
manufacturer.