Does anyone know how to get a Linksys WUSB54G to work on a wireless network using WPA? I can't for the life of me get it to work.

Right now I'm running BackTrack(Slackware based). I can't use wpa_supplicant because it doesn't work with rt2500.

The wireless assistant says it's WEP, and won't work with it; I even tried RutilT, but it said it was WEP too.

I used the following commands with still no luck,
iwpriv rausb0 enc 3
iwpriv rausb0 auth 3
iwconfig rausb0 essid "MYSSID"
iwpriv rausb0 wpapsk "MYKEY"
iwconfig rausb0 essid "MYSSID"

After that I tried using dhcp to get an address but didn't get anything.

Can someone please help me?

Oversimplified, but:

WPA consists of two pieces - 802.1x authentication and WEP with a frequently-changed key. You have to be able to do both to communicate with a WPA-protected network. No point in monkeying with the other parts until you fix that.

The 802.1x piece requires a program called a supplicant to handle the authentication with the access point. The only two options I know of are wpa_supplicant and XSupplicant.

If wpa_supplcant won't work (are you sure?), try XSupplicant.