\documentclass{article}
\usepackage{docassembly}
\usepackage{lipsum}

\hypersetup{pdfpagemode=UseAttachments}

% Look in the Adobe Acrobat JavaScript manual under the doc.importDataObject to see all the possible parameters.
\begin{docassembly}
% Or use \attachFile instead of \importDataObject
var retn = \importDataObject({
  cName: "job",
  cDIPath: "\jobname.tex"
});
% The next line creates a meaningful description of the attachment
if (retn) this.getDataObject("job").description="Source file for this PDF";
% You can have more than one file attachments  
var retn = \attachFile({
  cName: "AdobeDon",
  cDIPath: "graphics/AdobeDon.pdf"
});
% The next line creates a meaningful description of the attachment
if (retn) this.getDataObject("AdobeDon").description="The one and only AdobeDon";
% ...  
\executeSave();
\end{docassembly}

\begin{document}

\lipsum[1-30]

\end{document} 