There is a language= command line parameter to set the language (and %language) to use.
This will cause CS to construct certain folder names with that language name.
I don’t think there is specific documentation on the format of the dictionary files, but the existing text versions should give you enough to go on. The document on foreign languages has a bit more information.
If you decide to do this manually and not use TreeTagger, then you will have to do your own pos tagging and setting of canonicals (see the ^setcanon() function). We use TT, so perhaps others can jump in with their experiences.