To get wireless working under FreeBSD on Asus's EEE PC, you must first download the latest madwifi driver:
http://snapshots.madwifi-project.org/madwifi-hal-0.10.5.6/
Download the tarball and transport it to the EEE PC using removable media (USB drive, SD card, etc). Untar the tarball and then run:
# cd madwifi-hal-0.10.5.6-r3879-20081204/hal
# cp -R * /usr/src/sys/contrib/dev/ath/
Now recompile your kernel:
# cd /usr/src
# make buildkernel KERNCONF=GENERIC
# make installkernel KERNCONF=GENERIC
Reboot your system and you should see the following startup message (and in dmesg):
ath_hal: 0.10.5.6 (AR5210, AR5211, AR5212, AR5416, RF5111, RF5112, RF2413, RF5413, RF2133, RF2425, RF2417)
ath0: mem 0xfbef0000-0xfbefffff irq 18 at device 0.0 on pci1
ath0: Ethernet address: 00:15:af:67:d5:31
ath0: mac 14.2 phy 7.0 radio 10.2
Then simply connect to your wireless AP:
# ifconfig ath0 ssid <YOUR SSID> wepmode on weptxkey 1 wepkey 0x0000000000 up
# dhclient ath0
