My apologies. I assumed that you were talking about WB 2.7.
From what I recall, WB 2.6.7 didn't include the calendar popup, or even beginning and end dates in the news module. Perhaps some modifications have been made to the default WB installation?
Doing a quick Google search for the functions you mentioned in your original post lead me to believe that someone added the Date Input script found here:
http://calendar.moonscript.com/dateinput.cfmIf so, it appears that the day names, i.e. S M T W T F S, are set in an array at the beginning of the script. You could try changing the values in the array to reflect what you want, but I suspect that it will only affect the heading and not the actual day numbers; basically the day names and day numbers wouldn't match up.
I would suggest that you have your client upgrade to WB 2.7 since this feature is included by default.
Sorry I couldn't be of more help.
Nick