Step 1. Fill a shuttle full of Sith Assassins
Step 2. Exploit a straggler ship, begin doing as what happened aboard the Harbinger and start injuring crew, cutting them down to half-shifts, basically allowing the assassins more freedom of movement.
Step 3. Bring more assassins.
Step 4. Wait for the inevitable inter-fleet travel in order to perforate the assassins throughout the fleet and find their way to Revan's ship, bringing Kreia along who is no amateur to sneaking around.
Step 5. Assassinate Revan. What's the rest of the fleet going to do, send boarding parties? Against an invisible enemy and someone who could dispatch her own assassins with a four-second fade-to-black screen?
There is no strategy to confront what you are not aware of. And the knowledge that there are assassins is useless if you have no way to counter them. Aboard the Harbinger with one apparent Sith Lord in a tank, even when knowing Sith were aboard the ship, the Republic forces could do nothing to stop the slaughter that was to come. Very much the same scenario here because the fleet would not fire aboard Revan's ship. However, if the did, for some reason, then you would have your tie
Or perhaps the assassins are a diversion aboard the other ships, raising red flags and alarms everywhere, mass chaos, panic, allowing for Traya to subtly sneak into Revan's ship, assassinating him and then leaving.