I followed ChrisF here and write a simple demo.
...open your project in Expression Blend, select the button and then right click and
One of the great fetatures of WPF is the ability to leverage the behavior of a control while completely swapping the look of that control.You can just delete the chrome altogether and create a custom appearence that matches your requirement.
Sample
Check this too http://www.designerwpf.com/2008/03/27/wpf-designers-guide-to-styles-and-templates/
This link seems to work now: http://www.designersilverlight.com/2008/03/27/wpf-designers-guide-to-styles-and-templates/