I generally don't recommend using chmod(2)
for wireless, but that's my recommendation.. mostly due to the fact that switching between networks and configurations is a high probability with wireless, manual configuration makes more sense.
What you don't explicitly tell us is what happens after running ifconfig/dhclient, pasting the full output in [code][/code] tags.. both before and after you set the nwid and wep key in ifconfig.. will help diagnose possible configuration errors.
Are you bringing the interface up? does the connection establish? is a lease acquired? are you able to ping your router or other hosts?