well, install new liveries is quite simple, PMDG's guys make the installer very useful for us...I can make a repaint for the NGX with the repaint kit is providedbut, is there a way to create a file that the repaint manager can read? so, can I install my repaint via the repaint manager?

Yes. You need a later version of libery manager and export the livery with it.

ok, thankyou so much fabo!

After loading the textures into the appropriate fsx folder, update the cfg file, close the sim, open the livery manager, locate the livery you wish to export, then right click on it to export a ptp file to your desktop (or other location)

thankyou also to dennis!