Network failover to secondary gateway?

[MadCatMk2]

Hello everyone,
I was wondering if it's possible to set up a secondary gateway IP for my network.

The set-up is like this:
Computers are connected both wirelessly and wired to a router/modem (Thomson) TG585 v7 at 192.168.1.254
An Untangle box (192.168.1.67) running in Re-Router mode is also connected to the above router.
The computers are set to use the Untangle box both as DNS and Gateway.

So it's like PC -> Modem/Router -> Untangle -> Back to modem/Router -> Internet

With Windows it's easy to set up a the Gateway to the Modem/Router in case the Untangle box goes down, but I'm at loss with PCLinuxOS.

Here's the /etc/sysconfig/network-scripts/ifcfg-eth0 configuration.

Code:

DEVICE=eth0
BOOTPROTO=static
IPADDR=192.168.1.69
NETMASK=255.255.255.0
GATEWAY=192.168.1.67
ONBOOT=yes
METRIC=10
MII_NOT_SUPPORTED=no
USERCTL=yes
DNS1=192.168.1.67
RESOLV_MODS=no
LINK_DETECTION_DELAY=6
IPV6INIT=no
IPV6TO4INIT=no

Unfortunately setting "GATEWAY1" and "GATEWAY2" doesn't seem to work.

I wonder if this would be possible though the router's telnet configuration but I don't understand much from it.
Here's the available command groups if anyone has worked with a similar router firmware.

Code:

firewall        service         autopvc         connection      cwmp           
dhcp            dns             dsd             dyndns          eth             
atm             config          debug           env             expr           
grp             hostmgr         ids             igmp            interface       
ip              ipqos           label           language        mbus           
memm            mlp             nat             ppp             pptp           
ra              script          snmp            sntp            software       
system          systemlog       tls             upgrade         upnp           
user            wireless        xdsl         

I also wonder if KDE's network configuration control panel has such a capability - The network tool available in Xfce is quite limited.
Any idea is welcome =)