Recommendations for forward clicky switch - modifiable to two stage UI

I'm modding the tailend of a flashlight. One that doesn't have a tailcap to begin with and hopping to put one in. I want to make the job as simple as possible in terms of drilling/tapping/threading, so I'm looking for a simple "universal screw-in" (McClicky style) switch that is ideally a momentary two stage clicky. I know Surefire L1/L2 have them, but it appears that you cannot put these switches in a McClicky compatible light (they require that you use their outer housing)? Can a McClicky be modified to become a two stage switch? Are the SolarForce switches moddable compatible "drop ins"?

Thanks

By two stage, do you mean two output levels or a twistie with a momentary push button? Most multistage lights are controlled by a driver, and the driver sets the output. If the tailcap is used to switch modes, then there is likely something more then a simple switch there. The simplest might be a three state clickie (or whatever it is called) on-on-off instead of on-off. Have the second state go through a resistor for a lower output level, but IMO this is inefficient. I'm also not sure if that is available in a forward clickie.

FYI: the L1 two-stage tail cap is not a clicky, it's a twisty. The button only provides momentary on: press lightly for low, press harder for high. To get the light to stay on you tighten the tail cap until it turns on. It turns on in low, tighten more for high or you can press the button for a momentary high. As you turn the light off from high, either by releasing the button or by unscrewing the tail cap it goes to low before going off.

It gets so confusing sometimes. I'd like a PD or Surefire momentary UI. I've heard it called a two stage momentary clicky. I was under the impression that a two stage twisty would be a UI like the Aeon (no clicky to speak of).

I know of mods that add a resistor to the clicky to make it into a two stage. I'm wondering if this can be done with a McClicky? It would be interesting to have say momentary low, and full on click (non momentary) to high.