You can use
<xsl:template match="processing-instruction('SAE')">
<xsl:value-of select="." />
</xsl:template>
to match processing instructions named SAE
. (And <xsl:apply-templates select="processing-instruction('SAE')" />
, naturally)
The value of the instruction is not really XML, even if it looks like regular attributes in this case.
Processing instructions really only contain plain text, because they might be anything - from simple bits of information to complete programs in languages other than XSLT.
You can only get the content of the instruction, in your case the string 'page="ii"'
, which you then must parse manually.
You could do it in XPath like this:
<xsl:template match="processing-instruction('SAE')">
<xsl:variable name="start-token">page="</xsl:variable>
<xsl:variable name="end-token">"</xsl:variable>
<xsl:variable name="temp" select="substring-after(., $start-token)" />
<xsl:value-of select="substring-before($temp, $end-token)" />
<!-- output: "ii" -->
</xsl:template>