You just need to encode the xml string as a string so that you can include it inside of other xml... it's the xml equivalent of putting backslashes in front of your quotation marks when you put a "string" inside of a larger "string".

$xmlstring =~ s/\&/&/g;
$xmlstring =~ s/\</&lt;/g;
$xmlstring =~ s/\>/&gt;/g;
$xmlstring =~ s/\"/&quot;/g;
$xmlstring =~ s/\'/&apos;/g;
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That's all there is to it.