Perhaps if you could give a few more details it would help:
1. What wireless encryption are you trying to use - none, wep, wpa, wpa2, etc?
2. Could you try something like this: $ tce-load -i wl.tcz
$ sudo modprobe lib80211_crypt_tkip
$ sudo modprobe lib80211_crypt_wep
$ sudo modprobe lib80211_crypt_ccmp
$ sudo modprobe wl
$ sudo iwconfig eth1 essid "my_ssid"
$ sudo iwconfig eth1 key restricted 12:34:56:78:9A:BC:DE:F0:12:23:56:78:9A
$ sudo udhcpc -b -i eth1
..and then post the result of: $ dmesg | tail -20
Note that the above example is for wep encryption and the lib80211* modules names may have changed (this was for tc-2.x)