That site is now closed but here is the relevant info.
For widescreen resolutions outside of those shown in the setup program. use regedit to navigate to this key:
HKEY_CURRENT_USER\Software\Lionhead Studios Ltd\Black & White\BWSetup.
Look for two DWORD values in this key called ScreenH and ScreenW which are screen height and screen width .
Select the decimal button for the base and enter your desired screen width and height in each DWORD.
1680×1050. works well for me other resolutions by trial and error.