AFAIK there's no such thing as a "multi-color" font, there are some fonts you can find in both "filled" and "border" versions, so if you want to render it like a white font with black border you have to overlay one filled font color white and one outline font color black.
To complicate things some fonts are a bit different in their outline and filled version so some tweaking is necessary. One thing I did is I took a filled font and create the border version with fontsforge enlarging the existing font and placing it below the "white" one.