>the xml is not a well formed xml
I don't understand this statement. If it's not well-formed XML then it's not XML.
It's reasonably easy to export an Excel spreadsheet as XML. It's quite hard to process the resulting XML in XSLT because of its complexity, but it can be done.
Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference