The drivers are available for most PCMCIA cards, however FreeBSD 4.x typically doesn't work out of the box with PCMCIA cards. Wireless cards are generally an exception, but this might also be the case for some. Some customization to /etc/pccard.conf is typically required for the card to be detected. Google for your card model and FreeBSD and pccard.conf to find the required values if the card is not detected. You'll have to edit your m0n0wall image appropriately.