[--- Steps --]
BP on jump that decides on which message to show.
Patch that jump
Check MessageBox parameters and patch any wrong
parameters

[--- Wrong parameter 1 --]
push 0                 [ Button Type ]
push "Congrats!"       [ Caption ]
push "Well done!"      [ Text ]
push FFFFFFFF          [ Parent Window ]
call MessageBox


[--- Corrected Parameter 1 ---]
push 0                 [ Button Type ]
push "Congrats!"       [ Caption ]
push "Well done!"      [ Text ]
push 0                 [ Parent Window ]
call MessageBox

eax = 4 bytes
al =  1 byte