Specifying MAC address/physical address with XP Network Bridge

[CheetahMk2]

I created a network bridge with XP networking, but I need to generate a new MAC address/speficy a specific one for it to use rather than generate a static one. How would I go about doing this? The standard method of changing MAC has no effect;

If anyone could let me know how to specify the MAC address/physical address of a XP network bridge, it would help a lot. Thanks.

CheetahMk2

 

[CheetahMk2]

*crickets*