A while back, a few of us came up with a method to move the MsgBox window and to change button text. It was rather clumsy.
I wrote a dll solution for moving the MsgBox to the center of the parent GUI window that owned it for most of my personal work.
I decided to port it over to AutoIt rather continue to port the dll with all my AutoIt work, in addition I added the button text changing to the solution as well.
The examples should be self explanatory on how to use the functions provided.