need help for squid multy isp

[tomamodi]

hi!
I have two isp and two diffrent isp /gatway and lan
gateway
192.168.1.1
10.0.0.2

so i have to give ip for 192.168.1   /250
other                           10.0.0.1    /250

and two diffrent proxy servers squid
now i want to make one squid proxy server deal with both
some times one line d/c
i want squid deal this if find one isp dead it send req to other working
any one have any idea about please
just want squid  cache deal with both isp and both lan dual way
with out changing the ip in ie browser