Which H4 are you talking about? You should be able to solo all the heroic quests in Belsavis more or less as soon as you hit 50 as long as your gear is up to date (and SCORPIO's is for tanking Raxxus, since you're a healer).
Old Enemies / Raxxus is a straight tank'n'spank while you interrupt his heals, just stealth to him using sneak to get you past the first group of enemies + the roamer.
Freeing the Fallen is a H2 but He's only got like 70k hp and his damage is awful once you move from his AE. Stealth down to him and use sneak on the second group hugging the wall on the right for group1 and group3.
Lights Out is solo for any stealth user, you should be able to do this in about a minute flat without aggro once you learn the stealth pattern for it. Go from right to left using sneak on the first group of jedi to get you up the stairs and then just follow the ledges to get to the middle button (with the champion mob) and the leftmost button.