I have a KML file with polygon coordinates like:

(number1,number2,0 number1,number2,0 number1,number2,0 ...)

and I would like to extract them in the form of:

for this to happen I need regex and xsl:analyze-string for an XSLT
transformation, but I'm not familiar with regular expressions.

Has anyone used such a method..?

I wouldn't use analyze-string for this, I would do something like

<xsl:for-each select="tokenize($in, ' ')">
  <numbers>
    <xsl:for-each select="tokenize(., ',')">
      <xsl:element name="number{position()}">
        <xsl:value-of select="."/>
      </xsl:element>
    </xsl:for-each>
  </numbers>
</xsl:for-each>

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

Excellent! Thank you very much for your time :D