NITdroid finally managed to install both as the N810 N800!
The problem is that the file "flasher-3.0-static" is faulty!
Then, during installation, I made some changes:

I make a little difference in the installation. In nitdroid_complete.sh file it will download all the necessary files except the flasher (which is defective). If you use, it will stop soon after you partition the card and copy the android system on it.
Assuming you stuck at it, let's continue manually.
First, download this file in Linux (preferably Ubuntu, but can be a virtual machine that also works):

http://tablets-dev.nokia.com/maemo-d...2.5.2.2.tar.gz

Extract its contents and place the file "flasher-3.5" in the same location where the file is "flasher-3.0-static". Now, back to the first post and look at this manual step:

"To flash the kernel, use the command on Terminal Following:"
Replace with:
And voila! NITdroid here functioning both as the N800 N810!
Tip: I recommend using the manual installation, but the download script nitdroid_complete.sh to at least download all the files which would be required!

Be happy! ^^