OS client (Windows, Linux etc) doesn't set an encoding in a request. But eXo JCR WebDAV server looks for an encoding in a Content-Type header and set it to jcr:encoding. See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html, 14.17 Content-Type. e.g. Content-Type: text/html; charset=ISO-8859-4 So, if a client will set Content-Type header, e.g. JS code from a page, it will works for a text file as expected.

If WebDAV request doesn't contain a content encoding, it's possible to write a dedicated action in a customer application. The action will set jcr:encoding using its own logic, e.g. based on IP or user preferences.