Passing parameters for export to XHTML ?

I’d like to generate a XHTML file from Writer that contains some extra html tags. Namely I’d like to pass these 2 lines in the of the exported file:

<<script type="text/javascript" src="guide.js"></script>
<link href="CalcGuide70.css" rel="Stylesheet" type="text/css"> 

Can it be done by adding this content in the ODT file before exporting to XHTML? (where?)

Note: I prefer to avoid using extensions.