MAC address & rc.conf

[Peter]

   Hi,
   My ISP have aauthorization by username, password AND mac address.
   I currently make PPPoE connection from my laptop(win XP) to them.
   However I want to put FreeBSD router in front of my laptop.
   That is why I will need to make MAC address of outgoing ethernet card
   same as my laptop.
   I plan to make bash script(ifconfig down, ifconfig up)  for that
   purpose.
   However I prefer a little bit cleaner solution ...
    is there any way I can set MAC address for the network card in
   rc.conf ?
   Thanks :-)))
   Kind regards,
   Pete