Modify Mission Planner Speech Messages?

Is there any way to modify the text used for the speech messages in Mission Planner?
I have searched through the files in the mission planner directories expecting to find an ‘XLS’ file or something, but I cannot find anything helpful.
The reason that I want to do this is because the windows TTS has a poor cadence and it is very ‘robotic’ , so if I could make some subtle changes to the text the gets sent to the TTS system for various messages it would make the speech a lot more digestible to the human ear. Well my ears anyways.

Well…Since I was fixated on the “Pre arm” warning, which understandably does not have it’s own check box, I hadn’t even bothered with the other check boxes.
The last time I used the speech warnings was sometime last January, and at that time the Pre-Arm warning had a text error and it would say “Prearm” which sounded like Preermm, so I gave up on the speech function for a while…
So I don’t even know how long the custom text option has been available for the check-box items.
I still would like to change some things though.
I did adjust the Windows TTS speech speed which helps a bit.
FWBA & FWBB & RTL modes are painful to my ear.
I realize that Microsoft Anna has many quirks, but there are some ways to improve her diction.
If I change the mode message to {mode} MODE the “ESS” in “Stabilize” will sound slurred, but if the is a word in front of {mode} then the “ESS” is not mangled, mostly.
“Stabilize” sounds much clearer if you feed the TTS “staybilise” ,but the mode value that gets sent to the TTS engine is not accessible.
“voults” sounds better than “volts” ect…
Adding a comma helps to smooth the speech flow too.
I’m going to have to think about this for a while before I make any specific feature requests, but my initial thought is to used a user-editable-look-up-table.
Also, I found some postings on some other forum that supposedly claim that it is possible to add some the other Microsoft TTS voices to Window 7 even though Win7 won’t install them normally.

where did you find to do this? I found it once and now I can not find where I change these?