It might be more simple than you think.
I use an ral0 card, in 7.0 and, now, 7.1. But, I didn't have to use more than the following:
cat /etc/wpa_supplicant.conf
network={
ssid="NO-SSID-FOR-YOU"
psk=9ecd...
}
and, in /etc/rc.conf:
ifconfig_ral0="WPA inet 172.30.3.3 netmask...