OS: os2007HE
installed packages: xterm, gainroot, wireless-tools
step 1: get root access in a xterm
step 2: run these commands in the xterm:
ifconfig wlan0 up
iwconfig wlan0 key <your wep key>
iwconfig wlan0 mode managed
iwconfig wlan0 essid <your ssid>
ifconfig wlan0 <your ip> netmask <your netmask>
route add -net 0.0.0.0 netmask 0.0.0.0 gw <your default gateway>
echo "nameserver <your dns server>" > /etc/resolv.conf
gconftool -s -t string /system/osso/connectivity/IAP/DEFAULT/type DUMMY

In the above commands, replace "<blahblah>" with parameters of your network(without the '<' and '>'). Then minimo should work fine; when using any built-in applications and the 770 asks you to choose a connection, always choose "DEFAULT" from the list, and then everything should work fine. You can also put all the commands in a script to make it easier to run it again.

#! /bin/sh

# Script for controlling the WLAN connection.

# exit codes:
#   0: OK
#   1: you are not root
#   2: connection failed


# are we root?
if [ `id -u` != 0 ]; then
    echo "Only root may run $0."
    exit 1
fi

COMMAND=$1
USER=user

# set network name for wlan as saved in Connections
# only WEP, WPA preshared and NONE security
MY_NETWORK="HOME_WLAN"
MY_ESSID="HOME_WLAN"

# MY_ESSID=`su - $USER -c "gconftool-2 -g /system/osso/connectivity/IAP/${MY_NETWORK}/wlan_ssid"`

infoprint() {
    local msg=$1
    su - $USER -c "dbus-send --session --dest=org.freedesktop.Notifications /org/freedesktop/Notifications org.freedesktop.Notifications.SystemNoteInfoprint \"string:$*\""
}

bnep_start() {
    infoprint "Connecting to $MY_NETWORK ..."
		ifconfig wlan0 up
		MY_SECURITY=`su - $USER -c "gconftool-2 -g /system/osso/connectivity/IAP/${MY_NETWORK}/wlan_security"`
		case $MY_SECURITY in
				WEP)
	  	  		MY_KEY=`su - $USER -c "gconftool-2 -g /system/osso/connectivity/IAP/${MY_NETWORK}/wlan_wepkey1"`
						iwconfig wlan0 enc $MY_KEY mode managed essid $MY_ESSID
				;;
				WPA_PSK)
    				MY_KEY=`su - $USER -c "gconftool-2 -g /system/osso/connectivity/IAP/${MY_NETWORK}/EAP_wpa_preshared_passphrase"`
						iwconfig wlan0 enc s:$MY_KEY mode managed essid $MY_ESSID
				;;
				NONE)
						iwconfig wlan0 mode managed essid $MY_ESSID
				;;
		esac
		udhcpc -i wlan0 -n
		MY_IP=`ifconfig wlan0 | grep inet`
    infoprint "Connected with $MY_IP"
}


bnep_stop() {
    infoprint "Disconnecting from $MY_NETWORK ..."
		ifconfig wlan0 down
		udhcpc -i wlan0 -n
		ifconfig wlan0 up
}


case $COMMAND in
    connect)
        bnep_start
        ;;
    disconnect)
        bnep_stop
        ;;
esac