Well, I've found the problem with help from a guy from Nokia, but I haven't been able to fix it yet. Basically the problem is in making a tar file. The tar libraries that I've found for java are not compatible with the latest tar in the firmware. I hope we'll make some progress next week.
Indeed, the structure of the files from ThemeMaker is different from the default ones that do work.
Hmm, do these debs work for everyone ? I'm running the latest (sdhc fix) firmware on my N800 and i still get that tar error when trying to install the debs...
ive finally got nuvoblack working on the newest FW. thanks goes to suryavanshi for walking me through it , the way it wqas done , i believe any theme made with theme maker or an otherwise uninstallable theme on the new firmware can be installed in this manner.