Damn, beat me to it. Anyways, hopefully you have the skill or know-how to use a simple bonusmod system like the one provided.
That one will add your values. If you want to, say, give the unit a second attack you will only have the option to set up the second attack on the unit and then disable it. Using researches to enable it will help if need be and will be easy.
Otherwise use the Chaos ability to change the units attack types along with the bonus mods to help you. It's unfortunate but those are the only ways (That I can think of).
Good luck!