Hi,
I remember, that I was able to run BaseX as execution engine for the oXygenXML XQuery editor. This seems to be impossible since a few oXygen versions. All that's left is the WebDAV part. I did not manage to run my old config, creating new ones did not help either.
I remember having read a post by Michael Kay, who seemed to have some problems with XQJ not being up-to-date and some licensing issues making it impossible to fork/update or something like that.
The bug-tracker and mailing-list links on the XQJ site are dead as well.