Xolox was developed by a small dutch company named Beerenboot IT founded by four former students. Their emails never show up on any site related to Xolox, however here's how to contact them:

http://www.beerenboot.com/vennoten/midden.htm

At least Arno Steenbekkers and Michel Pasman are Xolox developers. I don't know for sure about the other two.

You might want to contact them, since they are going to release a new version of Xolox in several weeks.