Why not tune for meth and then use knock enrichment for when it fails?
You can implement it through CNOKT, but if your engine is highly tuned and already near to component limits then this won't help.
By the time it reacts and the boost gets pulled down enough there is a high chance you have bent a rod or done other damge.
Not to mention it will do this over and over and over again, because it will knock every time. It will also cause runaway knock because the knock will be so severe that it won't be able to pull enough in time.
When I get +100hp from meth, I usually have a lot higher boost and up to 8-10 deg more timing...
Hence why I said - either run a small jet and don't bother mapping for it, or do it right.
As for implementing mapswitching yourself - good luck. If you do not have experience with assembly and coding or microcontroller development, you are better off paying someone to do it for you.
but I would like to properly take advantage of it with more timing. I plan to use a microcontroller connected to a MOSFET and control the duty cycle of the pump to increase as boost pressure increases so I get more meth with more boost
Complete waste of time. Pressure does not equate to how much WMI flow you need. You will just have huge consumption and the engine will bog down in the midrange if you actually run enough of it to make a big difference, as you will have the same amount at 4000 and 6000 rpm, whereas engine flow is significantly higher at 6000 rpm.
There is one system that does everything right:
http://www.aquamist-direct.com/806-063-hfs3-v3-1-system-a-truly-progressive-system-utilising-pwm-valve/PWM IDC tracking, map switch output etc.
Everything else I have had the displeasure of working with has been quite bad.
What you are describing is not worth the hassle. Just save up some money, install Aquamist, buy a map switching solution and do it right the first time.
That's how I did it (minus buying the solution, as I write them myself), and that's how I do it for customers.
P.S.
I am not saying this because I want to sell you anything - I am just saying how it is. I have been installing WMI systems for years now.