(Caveat: Not sure of the software you are using, so I might be interpreting your issue incorrectly)
"Hopefully someone has done this already? Also my cal table only goes to 4.99v? When I try and change 4.99 to 22.39 it will only change to 9.68."
is a touch confusing. As you say, the voltage range of the MTXL is 0-5v, and the AFR range is 7.35:1 to 22.30:1. The voltage (between 0-5v) received by the computer translates directly to the AFR value it sees. It sounds like you are trying to change your voltage from 4.99 to 22.39? Of course one is a voltage, and the other is the max air volume value.
On my setup (ECMLink w/ MTXL), I'm using a LinearWideBand configuration. I did this because the value I was seeing on the gauge (correct) was about 0.5:1 lower than the value I was seeing in the link software. A minor adjustment to the minimum voltage value brought the DAC output inline with the gauge output.
Here you can see what the raw voltage and AFR looks like at WOT...
...and at full vac with my foot off the gas
The point is that your voltage should never be configured over 5v. 4.99v is fine, and if you see drift between your gauge and your computer, adjusting the minimum and/or maximum values is how you can get things synced up.
What's the software you are using? I'm applying my own logic from using link, but I don't know how it translates to your tool. And forgive me for over-explaining. You clearly know how the sensors work, but I like to put in extra info in case someone else who's new to all of this happens across this post.