If you slot an enhancement, you can middle click (scroll wheel click) and slot either: A) the same enhancement (e.g. Accuracy, Accuracy, Accuracy) or B) the next enhancement in the set (e.g. Positron's Blast Accuracy/Damage, Positron's Blast Damage/Endurance, etc.)
So slot Reactive Armor A in Fire Shield, then middle click in an empty slot in Plasma Shield. Slot Reactive Armor B in Fire Shield, middle click in Plasma Shield slot. Repeat as necessary.
You can do this multiple times, so you can slot Accuracy in as many slots as you want before you switch over to another enhancer, or if you're frankenslotting and putting Acc/Dams of the same set in every attack, you can do that, too.
