How can I remove the following line from my xml output:

<?xml-stylesheet href="template.xsl" type="text/xsl"?>

And how can I add a new line to my xml output:

<?mso-application progid="Excel.Sheet"?>

Detail description:

I have two XML files and they are transformed to another XML file with 
XSL. Here are the two input XML files:

template.xml (this one links to excel.xml)
------------------
<?xml version="1.0"?>
<?xml-stylesheet href="template.xsl" type="text/xsl"?>
<TEMPLATE_DATA>
    <EXCEL_XML NAME="TEMPLATE" LINK="excel.xml"/>
    <DATA>1000</DATA>
     ...
</TEMPLATE_DATA>
-----------------------

excel.xml
-----------------------
<?xml version="1.0"?>
<?mso-application progid="Excel.Sheet"?>
<Workbook xmlns:html="http://www.w3.org/TR/REC-html40">
...
-----------------------

Current output with my xsl:
--------------------------
<?xml version="1.0"?>
<?xml-stylesheet href="template.xsl" type="text/xsl"?>
<Workbook xmlns:html="http://www.w3.org/TR/REC-html40">
---------------------------

I want to remove the stylesheet and add <?mso...?> line.
So the desired output will be:
----------------------
<?xml version="1.0"?>
<?mso-application progid="Excel.Sheet"?>
<Workbook xmlns:html="http://www.w3.org/TR/REC-html40">
----------------------

HOW CAN i ACHIEVE THIS?

THANK YOU SO MUCH.