http://code.google.com/p/new-tab-jumpstart/Source code is there.
Working code is on 0.5a5, so if you want to try anything use that, trunk is not up to date.
If you have any questions I'll be more than happy to answer. To make it working just create a file named:
jump...@mihailo.lalevic
in profile's extension folder and put a path to the folder where you download the code.
So if your code is download in C:\tmp\jumpstart just put that into the file and it will "redirect" Firefox to look for extension there.
If you get stuck just email me directly.
Cheers,
Mihailo