If I use google to ask "How to change ICS addressing" I see that discussed so I won't write about that.
About the gateway. I wouldn't change that. But ICS is twitchy and I no longer support it. We use devices like the WGPS606 from netgear.com.
Sorry but ICS is a tar pit. You learn to throw a life line but never commit to fixing ICS issues.
I have a Linksys WRT54G router that works fine. In addition, one of the wireless clients has been set up to use ICS, sharing it's wireless connection with a wired adapter on the same client. My problem is that ICS insists on setting the gateway connection to an address of 192.168.0.1. Other client computers using that gateway are also assigned addresses in the 192.168.0.xxx sub-group. All client workstations are using XP pro.
Other wireless computers are assigned addresses (by the router's DHCP) in the 192.168.1.xxx range, therefore placing them in a different subgroup.
The result is that clients in the 192.168.0.xxx subgroup cannot see nor map drives on a client in the 192.168.1.xxx subgroup across the wireless router.
Does anyone know a way to get around this? If I try to move the gateway to the other subgroup, ICS stops workng. The router is hardcoded to supply addresses in the 192.168.1.xxx subgroup.