Colorblind WPF Spell Checker

Is there a way to use the default WPF Spellchecker to squiggly-underline misspelled words in a textbox control with a color other than red (like yellow)?

This is quite an important feature for our business application, as a lot of the people who use it are colorblind.

I've searched through stackoverflow, MSDN documentation, and many other sources with no success. In the end, I ended up loading characters and looking for how the underscore is underlined, but I couldn't find anything. Any help would be greatly appreciated.