I want to superimpose an "X" or line through the days already past the way I
do on my wall calendar.  Does anyone know how to do this?  

I would even settle for an alternative that would change the background
color of all days in the past.  Currently the current month's background is
one color and the previous and following month is in another.  Can one get
all days past to have one background color and today and all days in the
future to have a different color?  Even better would be to have all days in
the past one background color, today without background color and all days in
the future another color.