[R] Adding style sheet line to xml output

[Nick]

I'm probably being dense but I can't work out how to add the second
line:

<?xml version="1.0" encoding="ISO-8859-1"?>
<?xml-stylesheet type="text/xsl" href="style.xsl"?>
<catalogue>
...
...


I can get the first line using:

saveXML(xml$value(), prefix='<?xml version="1.0"?>',
encoding="ISO-8859-1")

Any ideas?

Thanks.