Well that is also what I found since the XFConfig-4 is global and changing it affected all users.
But, I had to ask as Linux keeps surpricing me as it can boot in so many ways and there
are so many things you can fiddle with so I looked in the documentation for X11 but
could not find any inforation of how to redirect it to another conf file.

Perhaps it is possible with some clever fiddling but Ill tell you if I find the way.

Thanks.