How do I recode an XML document in XMLSpy to use entities

Question

I have a rather large XSLT template which contains bilingual text (national characters in UTF-8). I am looking for a function that will recode all CDATA elements inside to use XML # entities, allowing me to store the XSLT as plain US-ASCII encoding.

Here is a basic example:

<?xml version="1.0" encoding="UTF-8"?>
<test>Soirée</test>

where é is encoded as C3 A9. The desired output would be

<?xml version="1.0" encoding="US-ASCII"?>
<test>Soir&#233;e</test>

where é corresponds to the codepoint for 'LATIN SMALL LETTER E WITH ACUTE' (U+00E9). Changing the encoding preamble on the first example results in an error as the UTF-8 bytes become invalid.

Is there a simple way to do this or do I have to resort to a macro?