iCal colors

I know how to change the colors of the different types of appointments (home, work, etc), but is there a way to change the base color of the calendar itself (where the full day appears), the left side banner where multiple months are displayed, or the top banner (where the day/week/month) appears? All are light gray which is a little drab. Thanks in advance!
-Brian

It's possible, but it takes the knowledge and willingness to open up the actual application files and swap them out.