Well, truth be told, I wouldn't have been behind the wheel, I would have just been a grunt writing missions.
That said, I don't know what a Scarlet Monastery is, but I can't imagine writing a scenario in which Revan and HK go down like bitches.
If I'd been told I HAD to include Revan as a raid boss, well...hrm. Zombie and Cyborg are a little obvious, but they'd get the job done. At a minimum, some setup where hey, it's been 500 years and he's emaciated and diminished and in some distinct way Not the Real Revan. Hell, maybe I'd crib the "resurrected by magic worms" plot from TMNT.
HK? Would totally find a way to use him, but not as a boss. I'd make him a mentor character for whatever the closest thing the game has to an assassin class is. Old and rusty and mad as hell and more caustic than ever.
The audition mod I wrote involved time travel and a causality loop. In hindsight, I probably wouldn't really go that route if I were on a Star Wars MMO. I also made some other mistakes; the thing was unwieldy and, as I mentioned, I didn't follow the style guide like I should have. And I based it around one character being an old war buddy and making some crack about amnesia if you say you don't recognize him; I thought it was funny but it really wasn't as elegant a way of shoehorning in a character who's supposed to be interesting as I initially thought.
The followup mod -- the one I sent in when it was too late and they'd already hired somebody -- was much leaner and more focused. I set it in the Mass Effect universe, some short time after the first game (the second hadn't been released yet) and involved the Keepers -- one starts behaving strangely and following you around. From there an elcor cop stops you and you end up being taken to one of the scientists who was researching Keepers in that sidequest in the first game. Since the Keepers were instrumental in the invasion of the Citadel at the end of the first game, suddenly his research has made him important; he's got basically unlimited research funding and has let it go to his head.
From there there are a handful of different ways to resolve the story, which I don't remember offhand (kill the Keeper, leave it behind, take it along as a Dogmeat character, things roughly along those lines). Maybe I'll post these things someday; they're rough (just characters standing around talking and appearing and disappearing, with some descriptions of what the action would look like if it were actually a game instead of just a dialogue exercise), but I don't think I'd be violating the NDA I signed unless I specifically described the rules of the audition or the spec docs BioWare sent me.
Anyhow. I guess what that says about me is I like things that are incongruous (like elcor cops -- you can bet I'd work a Wookiee Jedi in somewhere, and probably a hotheaded smuggler from Yoda's race) and I like to take minor sidequest characters and show what would happen to them a few years later given various stimuli (can't think of a side character from KotOR who would still be alive 500 years later and isn't a droid, but I'd give it a replay and bone up on the longevity of various Star Wars races). On the other hand I don't want to overdo that shit; I've already complained about how ME2 stretches credulity with its parade of cameos from minor characters in the first game. I live in the city where I was born, with a population of 162K, and I randomly run into someone I know from high school maybe once a year. If I wanted to reuse a character from one of the first two games, I'd want to make it plausible that, of all the gin joints in all the towns in all the galaxy, you'd walk into theirs.
(To that end I'd do everything I could to talk them out of including Tatooine in the game, because its entire purpose, as a backwater that nobody cares about and that Obi-Wan would find a suitable place to lay low for a couple of decades and keep Luke safe is eroded every single time someone puts it in a goddamn prequel. It would most likely be a losing battle -- without even playing the game, I'm going to assume Tatooine is in it? -- so then I'd revert to making the missions at least as pedestrian as possible. No big events of galactic importance; maybe some smuggling for the Hutts and the like.)