Just regular training with some emphasis on high end work. After the first sprint or two it gets really tiring if you're not fit. I can speak from experience on this one.
Get the lightest rear wheel you can get. Get an aero front one. If it was shorter than 0.38 miles, I'd just get super light wheels (at about 200-250 meters, but at 400 meters, aero will count up front).
Experiment with your wheel set up. You may find your sprint/jump style makes a different setup better.
Get an aero helmet or at least tape your vents. And practice sprinting looking down and being low.
Get a mid sized chainring, 50 or 51T, unless you'll run out of a 51x11 (43 mph?). It's possible depending on wind, grade, and you.
Start on the big ring, big cog (or thereabouts). Lowest gear for acceleration. Maybe have a hybrid cassette, one with a second position 21. So like 11-12-13-14-15-16-17-18-21-23 (the last two cogs, for campy, come as a set). Don't start on the biggest cog, start on the second biggest.
Practice shifting while sprinting. You should be able to get to top speed in about 100-150 meters. It's different sprinting from 0 mph and from 38 mph.
Practice getting up to speed in each gear before shifting. Experiment with in or out of saddle.
I'd lift if you eased off a bit. In 2 weeks of hard lifting, if you've tapered a bit, you can gain a lot of strength. Focus on upper body, core strength. If you're already maxed out, or if you haven't lifted at all, a bit of lifting might help. If you haven't been lifting it'll hurt for a week.
I think 400 meters is long enough that the strongest guy will win, not necessarily the best jump guy. A Cat 1 that could jump just as hard every single time (he wasn't getting fatigued) won the state sprint championships. Short too, about 150 meters tops.
Good luck,
cdr