No , taday it is not possible. All other forums answer it is not possible or it is too difficult. The k770i supports Flash menues, but when I ve flahsed only the FS from K770i on my K800i my phone did't want to start(white screen) so I put my K800i firmware back.

I think flash themes are not so important, becouse by trying to make the flash theme work on K800/k810 you can demage yor phone.

My recomendation is: change the Icons or put .gif's on the phone through them the menu looks like flash theme.;)