After installing the last EPM add-in version, and a little investigation in the VBA editor, we found out that the useroptions are manageable dynamically : api.SetUserOption ...
the only thing we miss now is the "name" or the "number" of available options ... (like I've said for example "refresh on context change" or "empty comments" field)
For the sheet options it is available in the EPM add-in help pdf file, but nothing about user options (2013-05-17 version).
It would be nice if someone could share about that.
Thanks in advance.