How do I get my (uninstalled) Xemacs to see (uninstalled) packages?

[Stephen J. Turnbull]

Alan Mackenzie writes:

 > How do I tell this XEmacs where to look to find packages?  Which variable
 > must I set, and is there anything more to do?  I've tried, but failed, to
 > find this info in the XEmacs and Lispref manuals.  Is it there, and if
 > so, where?

Documentation is in the node "(xemacs)Startup Paths".