How can I train for the swim portion of my super-sprint tri?

Swim more?!

You have plenty enough time to get better.  I'm an ex-horrible swimmer, but my advice would be to do all you can to get COMFORTABLE in the water doing the race distance.   So...swim more.  And take with you the confidence that you finished your last race (regardless of your 'personal life guard')  Good Luck

I agree...the only way to get to be a better swimmer is to swim more.  3 times a week go to the local Y and swim laps for an hour with breaks as needed and do a couple open water swims before the next race.  Work on freestyle and have a few back up strokes ie. side, back or breast, to fall back on if you tire form one. If you haven't had lessons I would definately reccomend that.  Even just one or 2 private lessons to have someone check your form and offer suggestiosn for improvement. Good luck!

Lesson's are a must IMO.  It's amazing what you can learn and correct in a couple lessons.

I was/am a terrible swimmer.  After one lesson I had a huge improvement in my form.  In swimming form is huge.  It makes you go faster and more importantly expend less energy.

With-in two lessons I pretty have my form down.  Now it's just a matter of improving it and getting stronger.  My last lesson I worked on my breast stroke and side stroke.   Between those three and the back stroke (basically freestyle on your back) I have 4 swim strokes that use muscles differently to fall back on during the swim.

I'm still a terrible swimmer, but now I have the confidence of 4 different strokes to get me through.

FIND A GOOD COACH TODAY!

Like others have already posted get more pool time in. My first three triathlons all involved conversations with the lifeguards. I was never offered a noodle, but I was offered to grab their kayak if needed. My goal for this season was to complete a sprint with no lifeguard conversations and no backstroke. What worked for me was frequency on pool workouts. Most of my swims are during lunch and only 20 minutes long, but I can get 4-5 of them in during a week. I started swimming 50 yards and then taking a break. In a few weeks I was swimming the full 20 minutes non stop. Knowing I could do that gave me a lot of confidence on a 1/4 mile swim. I've completed two sprints this summer with a 1/4 mile swim and completed both without lifeguard intervention or backstroking which was my old panic striken fall back position. That includes the last race where someone from the following wave grabbed both my feet and pulled them down. If that would have happened last year it would have been full out panic time. This year with the extra swimming time and confidence it was just an annoyance that threw me off my rhythm.

I think you'll have a breakthrough in just a few weeks if you put the time into it.  I'm no expert, but I'm in the same boat.

My first swim lesson was on July 7 and I could barely swim 50 yards.  It's true that just a few lessons with a lifeguard's guidance is a HUGE improvement. 

I finished the class and dilegently swam 1 hour 3 times a week building my distance using the ladder technique.  I used breast stroke when I got winded.  I totaled 1900 yards this morning (with a few short breaks) and have little need of the breast stroke anymore.  

You have time.  You CAN do it.  Get some pointers on form.  Swim at least an hour 3 times a week.  Build on your laps (I really liked the ladder technique).  Use other strokes as needed but try to start eliminating the other strokes as you get better.

Think... slow and steady, long and lean!

Well if it's as bad as you describing... you need to get a swim coach. Honestly, even it it wasn't that bad, I would still say get a swim coach.

Learn the proper form the first time around. Don't flounder in the water for a year... learn bad habits and then go get a coach... only to have to relearn everything.

In 6 weeks the swim coach can help you a lot. You might want to try for lessons 2-3 times a week.