To automatically create a station mode interface called ath0, add the following lines to /etc/modprobe.conf:

• alias wifi0 ath_pci
• install ath0 /sbin/modprobe ath_pci; /usr/local/bin/wlanconfig ath0 create wlandev wifi0 wlanmode sta
• remove ath0 /usr/local/bin/wlanconfig ath0 destroy; /sbin/modprobe -r ath_pci

If /etc/modules.conf has a line: alias ath0 ath_pci remove it.