There are several different ways to go about doing it. It depends on how you are tuned (and there are also completely standalone systems).
If you are on AP, I believe that is already a feature that is built in?
If you're on Open Source (ie Tactrix cable) it's a lot more fun because there's a thing called MerpMod which is essentially a completely hacked patch for a rom that was develped by people that extend the functionality of the ECU (including things like 2step, flat foot shifting, rev limiter replacement, speed density tuning and future features such as having a light blink in your dash if your car experiences a knock event for example).
I'm on the Open Source side and I have a Merp Mod patched rom which I tune myself and I'm very happy with it (although to be honest I rarely use the actual 2step).
Parallel to the 2step in MerpMod, I run something I think is way more fun but it's a complete hack (a very clever one at that) but it works incredibly well. This method works with both AP and Open Source and delivers the exact result you're looking for, what's more is it builds significanly more boost than a 2step alone (even without using 2step) but can be tuned to work well WITH 2step to have significant boost and a controlled RPM during launch.
Here's how it works, dumbed down: You add a relay and a button to disconnect the temperature sensor in your MAF assembly. What this does is signal to the ECU that the outside temperature is -40 degrees (which would obviously never happen). Now you have a trigger for tuning, because you can set up the maps that deal with timing compensation tables that are relative to the intake air temperature. You can now use those tables to retard timing ONLY above a specific RPM range, and ONLY when the button is active.
Now you not only have Anti-Lag for launching where you can reach pressures above the spring rate on your turbo (I've seen numbers around 15psi, it's less with my EWG but I was thinking about adding another solenoid control to redirect boost source to the top port to push it closed when the Anti-Lag is activated).
The reason I use this and not 2step with it is because the timing is retarded, the motor revs up much slower, so it's pretty easy to catch the exact wanted RPM as you drop the clutch.
Obviously this puts a good amount of stress on the motor and turbo and exhaust... but I recently had the joy of rebuilding mine for other reasons and the turbo had zero shaft play and exhaust were fine (motor was toast for other reasons but the valvetrain which is what this mod would affect was fine).
Anyway just a tip, it works great. Here's a link: https://forums.nasioc.com/forums/sho....php?t=2540082
Here's my real world result (catless, with around -20 degrees retarded timing when active)