Are you able to snag the ratio character you refer to and send it to me via e-mail?
In any case, the following regular expression should catch the time as shown by Microsoft no matter what the character used between the hour and the minute:
and use the following replace string to get it pronounced correctly (note, I am going to presume that the backslash is used as the match string notation, if you regular expression interpreter uses the dollar sign substitute it where I have a backslash):
\1 \3 \4 \5
this would take the string "6:37 PM" and break it up as "6 37 P M" for the synthesizer.
Here is a test to find out whether your mission in life is complete. If you’re alive, it isn’t.
~ Lauren Bacall