Change LAN IP with Plusnet flashed Thomson

[#1]

Hi,
Just become a Plusnet broadband user with the Plusnet flashed Thomson TG585 modem/router. As I have a compulsion to change from defaults (don't ask!) I have already changed the SSID and WPA key, but the LAN network address seems difficult to change. I have searched recent posts but not found an answer - the nearest was a Plusnet suggestion to use CLI 
Having backed-up the configuration settings and previously configured a Netgear DG834GT to use WPA2 by editing and reloading the configuration, I looked at the file and it appears that a global replace of "192.168.1." with "192.168.x." will do the trick while adding
    primdns=<ip1> secdns=<ip2>
to the end of line starting
  pool config name=LAN_private
in section "[ dhcs.ini ]" would change the supplied DNS server addresses (to a local system).
Does anyone have experience of this or any comments before I "brick" the router by trying (It appears to be Linux based, so I expect it will accept a "factory reset" whatever the config file screws up).

[#2]

Hi.
I gave the router the 192.168.1.1 address by clicking Home Network ( bottom left of screen) > interfaces > local network then configure in the top right hand corner. Only problem I found which I haven't bothered to look into yet as my machines are on static IPs is that  the DHCP server still gives a gateway address of 192.168.1.254 even though it replies to pings and web interface is reachable on the .1.1 address.
Cheers
Jon

[#3]

Thanks for the reply, Jon. I wish to use DHCP and need to set the correct gateway so that visitors (sons) can use the net if needed.
I have finally tried editing the saved configuration file and, after a restore configuration and power-cycle reset, now have what I need. All very painless, really 
Now to try additional things, such as different pools for ethernet and wireless - just because it seems possible.
Phil

[#4]

Its odd but when I set mine up with 192.168.0.66 as its address (to fit in with the DHCP server which was running elsewhere) it just worked.
I went in and looked just now and the thomson thinks it has the following addresses:

10.0.0.138/24 Static
192.168.0.66/24 Static
192.168.1.254/24 Static
which might explain why it works with a different gateway address than you expect.