No problem, and I've tested it this morning on my 808 (successfully).
1) you extract the original rofs2 file which have the writing language you need using Nokia Cooker for that
2) copy all these file to their appropriate folders in your CFW
sys\bin\ptikeymappings_itut_*.dll
sys\bin\ptikoreanqwertycore.dll
sys\bin\ptivocore.dll
sys\bin\ptixt9kdb_itut_*.dll
sys\bin\xt9*.dll
private\10009d8f\ecom-2-*.spi
private\10009d8f\ecom-2-*.s*
resource\peninputmodeswitchutilsnew.r*
resource\plugins\peninputgeneralitutnew.r*
resource\plugins\peninputgenericitut.rsc
resource\plugins\peninputitutconfig_*.rsc
resource\plugins\peninputsplititut.rsc
resource\plugins\peninputsplititutconfig_*.rsc
resource\plugins\peninputsplititutnew.r*
resource\plugins\peninputssqwin.r*
resource\plugins\peninputssqwinconfiginfo_*.rsc
resource\plugins\peninputvkbkrwindowkr.rsc
resource\plugins\peninputvkbwindow.r*
resource\plugins\peninputvkbwindowconfiginfo_*.rsc
resource\ptiengine.rsc
(some files may be missing, it's not a problem)
You can replace all these files with the ones in your CFW except for the ecom-2-*.spi or your language files will be corrupted so when you put these files rename them to higher grade which means if you have copied file ecom-2-0.spi to its appropriate folder, do not replace the original one , instead, just rename the copied one to ecom-2-1.spi.
The easiest way to do that :
1) I create the /sys, /private/, etc. minimal tree for the language to be added
2) I copy the files above
3) I drag and copy the three main directories in the target rofs2
I've just added Finnish to euro1
