You'll want to add a query to your product xml package that selects the individual item shipping cost and pass in the productid as a parameter:
They will become available in the XML and you can then transform them in the XSLT.
<query name="Shipping" rowElementName="Cost">
select SomeValue as Cost, SomeValue as Method from SomeTable with (NOLOCK)
You'll want to create a new template in your XSLT:
and then call it from wherever you want it to display in the package:
<xsl:value-of select="Method"/> : <xsl:value-of select="Cost"/>