Enabling restricted units

Right, so we all know Britons do not have access to gunpowder units except for the Cannon Galleon. I am attempting to make a scenario in which you can train Hand Cannoneers in Feudal age and Bombard Cannons in Castle Age. Before you all tell me they can't be trained that early, I'm aware and it's possible to enable them for civs who already have access to gunpowder, like Italians and Japanese. Without enabling all techs, is it possible for this to be done, and if so what are the tricks I need to do. I'm already using Trigger Studio and have used some of the expanded technology lists, so anything based around that would be preferable. I don't want mods for compatibility purposes. Any ideas?