Real Time Editing?

[Squirrelloid]

Well, you can boost gems with your modding trick, by making a recruitable unit generate gems. I don't think you can do that with gold however. (Of course, cheaper units cost less to buy and require less upkeep, so that's sort of like generating gold)

[RadicalTurnip]

You could also mod wish to alteration 0 and to cost 1 gem. That is pretty much a cheat code, as you can wish for gems, blood slaves, gold, dominion, or specific units you may want to toy around with.