Mike,
Have a look at a previous response to a similar question on this forum at http://www.biztalkgurus.com/forums/t/9651.aspx
However, you will need to modify the XSLT so that it reads:
<xsl:value-of select=”//Page[@number = 1]/TBox[@id = 63]/Value” />
Note: this just returns the value of the <Value> element only where Page = 1 and TBox = 63
Regards, Nick.