It seems that it is possible to install Duokan'12 on Kindle 4 with just a restart using the well-known data.tar.gz method. ( does anybody confirm that they include a special data.tar.gz in the zip for Kindle 4NT ? )
quoted from duokan.com
Duokan2012 two-step installation
Install "to look at 2012 to the Kindle 4, only need to manually reboot the Kindle. Do not need to use the installer does not need to enter debug mode.
1. To copy DK_System and data.tar.gz (in the windows system, data.tar.gz possible to hide the default format, display only data.tar, this is normal)
1.1 Connect USB cable, to copy DK_System folder to the Kindle disk.
1.2 the copy data.tar.gz Kindle disk.
1.3 pop-up Kindle disk.
1.4 Unplug the USB cable.
Manually restart the Kindle
2.1 the Menu button -> select Settings -> click OK -> again button in the Menu -> select Restart
2.2 restart automatically release and run the installation script. Kindle automatically enter to see more of the installation is complete, please be patient, the installation process takes about five minutes (during the installation process will appear to install the interface)
Note: must be in strict accordance with the previously described steps, the first pop-up the Kindle disk, and then pull the USB cable.
If unsuccessful, once again copy data.tar.gz and repeat Step 2 can.