If you want the combat log to denote both HP and MP restoration, that, I'm not 100% sure how to do. Otherwise, the simplest way I can think of would probably be to create a function that you could put into the formula bar in lieu of what is normally put there. As a quick example...
function healMPAlso(base, a, b) {
value = base + 4 * a.mat; // Healing skills tend to ignore DEF/MDF values
b.mp += value;
return value;
};
...this code could be used in conjunction with a skill that is set to "Restore HP". However, as noted, the combat log would only output the amount of HP that was restored this way.