This really requires someone who knows the language to contribute an implementation of an algorithm, or at least find an existing algorithm (e.g. in a paper or an existing non-Snowball algorithm with a compatible licence that could be reimplemented in Snowball) that could be implemented (though that also requires someone to find the time to implement it, so is likely to take much longer).
I noticed that http://members.unine.ch/jacques.savoy/clef/ has a stemmer in Java (two actually, but I think they're equivalent and one uses literal Unicode strings while the other \u escapes).
This really requires someone who knows the language to contribute an implementation of an algorithm, or at least find an existing algorithm (e.g. in a paper or an existing non-Snowball algorithm with a compatible licence that could be reimplemented in Snowball) that could be implemented (though that also requires someone to find the time to implement it, so is likely to take much longer).