setup wireless networking on slackware

Just wondering if you have tried running the dhcp client on wlan0 to see if it obtains an IP address automatically.

You have no encryption key in your rc.wireless.conf, is there no encryption in place? If there is you'll need to add it. Also, try connecting without specifying a channel:

VERBOSE=1
case "$HWADDR" in
00:22:43:*)
    INFO="Multiband Atheros based 802.11a/b/g universal NIC"
    ESSID="rmitvnnet"
    KEY="s:password_here"
    MODE="Managed"
    ;;
esac

Change password_here with your wireless key. If it still doesn't work, try setting the channel (if you know it).

You may also be interested in wicd. It is way easier than messing with rc.wireless.conf: