Customize the buttons in Views Navigation widget with third-party icons

[JingchaoZhou]

Hi, 

I am wondering if it is possible to replace the buttons in the Views Navigation widget with icons from a third-party lab or other resources in the dev edition. For example, there are 4 buttons in the sidebar (which contains a Views Navigation widget), and I want to replace the print button in the screenshot with a 'printer' icon, and replace the direction button with a 'car' icon. Is this possible? Thanks!