If you want to hack in something the like of having tokens (that keep re-rolling until hitting, as per how tokens work) allocated to some specific researches, and as many at the same time as money can buy, you can hack it by creating boxes in the game, where to put units, acting as pseudo-token resources, and, then, triggers that have a chance of removing those resource-like units and giving you the tech. Or you can make it just like AoT, but, instead of the triggers removing the pseudo-token unit and giving you the tech for sure, you can have them related to rolling a chance to do it (with different chances the more the units of that kind you have around, like buying more tokens (you just need more triggers)), and removing them and getting the tech only upon a successful chance. Not really directly possible with user actions and resources only (like clicking on a user action button for a chance to get a tech), because the only resource that the user action sees are the PUs (but since you can see units, you can hack this, as well, by placing units acting as pseudo-tokens, and having user actions conditions looking at those).
If you go this way (like AoT, but with chances to remove the unit and get the tech, instead of just 100%), I would also suggest, instead of having the pseudo-token unit laying around till scoring a hit on its tech, having it also a maintainment cost per turn, lower than the initial cost of buying it, since it doesn't really make sense (as per how the token system works) that you buy the tokens and fail, then further researches cost nothing (but time); they should cost less, but there should be still some cost, realistically. However, this would add the need of having the ability to remove the tokens you want to stop researching (again, more realistic than surely keep researching what you started till success), if they are not free to roll again; you can remove units with user actions.
To make it clear, limited to only simulating a tech token system with the variation you wish, you can start from Frostion's AoT and change it this way:
- You spend PUs or whatever instead of the specific tech resource to buy the "tech-units" (to have the trade off between more tech and more money, differently from AoT, where money and tech are set apart).
- You can buy (and place) more than 1 of the same "tech-unit".
- Change the triggers to have only a chance to remove the tech-units and giving you the tech, instead of doing it for sure (so, the unit would just act like a token that you keep rerolling, but specific to the tech you bought it for, as per how it works in AoT); sadly, here there is the problem, with conditions, that you cannot directly test for the number of such tech-units in the map, but only for the number of them in a territory or the number of territories having them (so, if you want to keep it simple, you can have a "box" territory, in the game, where to place all tech-units, instead of placing them like all land units, as per AoT).
Still, at this point, I think that adding something to have some more costs for rerolling (the tech-unit having an upkeep cost) would be foremost to enhance realism, even tho it would make the system more luck dependant, as if you fail to get the tech, you would lose also more money, instead of just time.
There may be other ways to hack something the like, but I'm guessing that this (using tech-units and triggers testing their presence, like in AoT, but in a more complex manner) should be the closest way for what you want, if I get it.