To disallow tech' gains through conquest, you 'toggle' this variable in the scenario parameters...
Cheat > Scenario Parameters > Edit Special Rules > Forbid Tech From Conquest (1)
To disallow tech' exchanges, forbid negotiations between the relevant tribes.
Alternately you can use the 'give technology' action in the events to ensure that certain technologies once received by a particular tribe will trigger an event that gives them a 'no,no' advance. This is a little confusing, and would be best explained with a lengthy example. While not perfect for this exercise, the section in
sleague.apolyton.net/Guides/sldt_govt.shtml that is titled 'Quarantining Governments - Events' demonstates how 'Socialism' could be traded, but 'Communism' (a 'no,no' advance) is only obtainable by the East Germans. Please get in touch with me
c.hills@bigpond.com if you need this explained further.
To permit tech' gains through theft, provide diplomat/spy units. Be wary of using diplomats in scenarios - they can cause havoc at times, particularly if one tribe builds up a good cash reserve.
As for your idea/theme - it sounds terrific! I also have never heard of it, but with some good graphics and a lively events file, this could be a superb game.