The latest version of Civ3CopyTool has an export to bic function. That can then be loaded into the Civ Editor and you can add your resources. Then start the game as a scenario.
I've done this, but it wasn't entirely satisfactory. I used a large map and after editing it and restarting I had rampaging barbarians instead of the sedentary I started with. Also the corruption was much increased as if the edited large map had the corruption settings of a standard map. I played it out and won big time. But, I haven't tried it since.