unfortunately you can't use Duokan lite (the latest version). It is only for kindle 3 now.
The last version of Duokan you can use can be found here. http://flip.netzbeben.de/2010/11/duo...ish-gui-today/
PDFs look slightly worse than the original kindle firmware. But it has enhanced abilities like, reading TOCs, half-page or quarter-page views, full-screen mode, adjusting the level of black, manual zoom etc.