On the solo/story-mode Spirit of Vengeance Flashpoint, I am able to fight the final boss for the most part. However, she will exit the stage twice and adds will come on. I can deal with the first wave of adds just fine, but the second wave with the sharp-shooters keeps killing me. What should I do to beat this wave?

I had to micromanage my companion, because he does not seem to target those adds. Either set him to tank or heals to back you up and force him to target at least one enemy from that crowd. He will focus on the boss even when she is not in the arena.

Put comp at heal.

Command comp to attack the sharpshooters. You should attack that one too to make it faster.

You have to manage kolto stations. Keep an eye on yours and your comp's hp and remember where the kolto stations are, if either of your hp hit 50%, go for the kolto station. The key in this part is to keep you both alive long enough to take out the sharpshooters.

Oh, and don't forget to buy and use a "Command" (== +Presence) stim from the medical service droids to give Rass a lift.