ragazzi problema risolto
ho sviluppato questa procedura:

codice:
private sub scriviXML()
Dim wrt As New MXXMLWriter40
Dim domDoc As New DOMDocument40
Dim atrs As New SAXAttributes40
Dim cnht As IVBSAXContentHandler

domDoc.async = False
domDoc.validateOnParse = True

Set cnht = wrt
wrt.output = domDoc
wrt.indent = True

cnht.startDocument
cnht.processingInstruction "xml", "version='1.0'"

atrs.addAttribute "", "", "xmlns:xsi", "CDATA", "http://www.w3.org/2001/XMLSchema-instance"
atrs.addAttribute "", "", "xsi:noNamespaceSchemaLocation", "CDATA", "myXSD.xsd"

cnht.startElement "", "NODO_1", "NODO_1", atrs
atrs.Clear


cnht.startElement "", "NODO_2", "NODO_2", atrs

cnht.startElement "", "NODO_3", "NODO_3", atrs
cnht.characters "0"
cnht.endElement "", "NODO_3", "NODO_3"

cnht.endElement "", "NODO_2", "NODO_2"

cnht.endElement "", "NODO_1", "NODO_1"
cnht.endDocument
domDoc.save "c:\testXML.xml"
end sub
grazie ancora