Altered Time - your #1 World of Warcraft Mage resource!

I'm trying to make a single weakaura that tracks chain reaction and changes the progress timer's color from white to yellow at 6sec and red at 3sec duration remaining. Supposedly, you can do this by going to animations > Main > Custom, then tick color > custom and enter the lua code. My knowledge about code stops there and I couldn't find a proper string online that does this.

P.S.: As a bonus, having this functionality for personal debuff tracking on a hostile target would help as well.

Thanks for your (altered) time .

EDIT: Figured it out, for those who care: you can circumvent the whole custom code approach by adding conditions.