#\DeclareLyXModule[endnotes.sty]{Adds an endnote command, in addition to footnotes. You will need to add \theendnotes in ERT where you want the endnotes to appear.}{Endnote}

Format 5

InsetLayout Custom:Endnote
   LyXType	custom
   LatexName	endnote
   LatexType	command
   Decoration classic
   Font
     Size	Small
   EndFont
   LabelString	endnote
   Preamble
     \usepackage{endnotes}
   EndPreamble
End