Hey!
Hm, out of the box, an effect like that isn't possible. If you're handy with shaders though it would be possible to edit the two types of outline shaders that come with STM to have additional colour passes! The "Universal" shader would just need more passes added that reference a different colour, and the "Ultra" shader would need... probably just a couple more calls to the function that draws outlines, but with different distances & colours.
Eventually I'd like to extend the new Ultra shader to be able to support effects like this (outline & dropshadow at the same time is planned first, though!) but it's not a very common effect for dialogue text, so there's other things I need to prioritize first, sorry!
Oops, sorry about that broken link, should be fixed now! How long was that there for...?
Thank you for your inquiry!
-Kai