I tested to add the xt9 Dutch dictionary, all it all worked OK. The only difference is like many guys said before you have to increase the language count to 16 (I was only lucky when adding the portuguese because portuguese is language number 6 in xt9). You will be choose among several languages, but only the ones that are properly set in the registry will work.
The files I putted in Windows folder were:
- NLlsUN_xt9.ldb
- hpd.5x4.Dutch.kdb
- spd.5x4.Dutch.kdb
XX for Dutch is 13.
Add REG 0613 to HKEY_LOCAL_MACHINE\Software\Tegic\eT9\IME\KDbFiles with value hpd.5x4.Dutch.kdb.
Add REG 0113 to HKEY_LOCAL_MACHINE\Software\Tegic\eT9\LDbFiles with value NLlsUN_xt9.ldb.
Add REG 0A13 to HKEY_LOCAL_MACHINE\Software\Tegic\eT9\Sip\KdbFiles with value enhpd.kdb. -> Here you can change to the one of your language, but the alphabet is the same as the english one there's no need. But for example for Russian you will need to change it and then copy the extra file.
Add REG 0B13 to HKEY_LOCAL_MACHINE\Software\Tegic\eT9\Sip\KdbFiles with value spd.5x4.Dutch.kdb .
Now go to xt9 options and choose Dutch, and you're done.
Hope this helps.