folks - i have used the "400plus" hacked firmware -
Like ninja2 said - ISO3200 is very noisy.
(that camera ain't great at even ISO1600)
there is no live view or movie mode.
Hacking the cam in my view has limited application for astro -
400plus has an intervalometer - you can use this for timelapse stuff.
(here's something i did a few years back)
https://www.youtube.com/watch?v=mQSybwliwu0