No. :(
I hacked that thing to pieces to get it to do what I wanted to, and by the time I realized that I was doing a great disservice to Europeans by starting the week on Sunday, it was far too late to make it a configurable option.
I'm wondering if you would have better luck with LiveCalendarWidget. The advantages being:
1) It's PHP based rather than Javascript based, and I believe PHP's locale awareness will return Monday for the 0th day of the week, but I'm not sure.
2) You can create your own template. Just copy the LiveCalendarWidget.ss into your theme directory templates/ folder, run a build, and hack away!