I confess, I seldom do well at fireworks - it's a mental thing - Most defeated photographs happen in your head before you even press the trigger.. This time, I had a more positive outlook.
I started at f/11 but I moved onto f/22, the smallest aperture I could go, and the lowest ISO my camera could do -ISO 200, I didn't like bleached out trails and overwritten trails so on Ockert's advice of using a black masking board, I brought my Olympus polyprop environmentally friendly bag, tied the strings around the tripod head and laughed as I played peek-a-boo blacking out the scene between bursts.
Oh and turned on Olympus's unique Live Time - the feature that +Trey Ratcliff was asking for on his NEX.
Does Live Time really help? It sure does. You can "see" when you are getting too many bursts superimposed and when the white trails which are so much brighter, are bleaching the scene so that you can end that frame and start a new one.
But you must set the refresh frequency right. For this series of cameras, you can only refresh the LCD 24 times. If you set it at 2 secs refresh and you use a black mask in front of the lens to keep the exposure running but not take in more light, you could have the shutter open for way longer than 48 secs. (there is finite limit to the number of refreshes). Something like 4 secs at this fireworks density is about right - if you have more fireworks bursting per sec, then you may not hold the shutter open for that long).
And so, Enjoy!