Include _entypo-svgs.scss in your project and have a look in example.scss how it's used.
At the moment, june 2015, the only way to change fill color of the SVG on :hover (with this method) is by including the SVG code once again with the entypo-icon function and set a new color. This is not recommended though because your CSS file is growing in size everytime you add SVG code to it.