Biodu, yes it works perfectly to run Duokan on DXG with firmware 3.1 as I wrote in an earlier post. I first updated both the DXG 2.5.8 and the Kindle 3G with Duokan before extracting rootfs.img and creating the update package. You need to be patient first time when you restart since it takes some time during the initial boot screen for Duokan to index your documents and music. I think my previous problems were due to my impatience. So if you just can borrow a Kindle 3.1 (or use the method below) I think there should be no problem.
An alternative
method - which works both with and without any binary installation of Duokan (in the latter case just copy the DK-folders to the USB root directory of the Kindle) - is to start up Duokan within Kindle environment using
Launchpad. It is very convenient and much faster than to reboot everytime you want to switch from Kindle OS to Duokan. Just put attached startdk.sh in DK_system folder and attached duokan.ini in Launchpad folder and reboot. Then you start Duokan with [Shift][Menu] (within the Kindle OS) and move back to Kindle OS with [Shift][Back] (keys should be pressed in rapid sequence but not simultaneously). It takes still some time so be patient after Launchpad states "Success".
I also include a browser.ini to be placed in Launchpad folder. Then you start browser from any screen with [Shift][Home]. Finally I start
mplayer from Launchpad using mplayer.ini. Use [Shift][Up] on four way controller to start the music, [Shift][Down] to stop the music, [Shift][Right] to advance to next song and [Shift][Left] to return to previous song.
I have had some problems that Launchpad stops working. I think it is when Kindle powers down automatically. I need then to reboot to make Launchpad active again. To make Kindle OS default during reboot you can "Set DK System" in Duokan settings to Off