Look for the docbook-xsl directory in /sw/share/xml/xsl/docbook-xsl,
because that's where the Fink distribution for Mac OS X puts it.
MERGE TO STABLE
dnl ** check for DocBook toolchain
FP_CHECK_DOCBOOK_DTD
-FP_DIR_DOCBOOK_XSL([/usr/share/xml/docbook/stylesheet/nwalsh/current /usr/share/xml/docbook/stylesheet/nwalsh /usr/share/sgml/docbook/docbook-xsl-stylesheets* /usr/share/sgml/docbook/xsl-stylesheets* /opt/kde?/share/apps/ksgmltools2/docbook/xsl /usr/share/docbook-xsl /usr/share/sgml/docbkxsl /usr/local/share/xsl/docbook])
+FP_DIR_DOCBOOK_XSL([/usr/share/xml/docbook/stylesheet/nwalsh/current /usr/share/xml/docbook/stylesheet/nwalsh /usr/share/sgml/docbook/docbook-xsl-stylesheets* /usr/share/sgml/docbook/xsl-stylesheets* /opt/kde?/share/apps/ksgmltools2/docbook/xsl /usr/share/docbook-xsl /usr/share/sgml/docbkxsl /usr/local/share/xsl/docbook /sw/share/xml/xsl/docbook-xsl])
FP_PROG_FO_PROCESSOR
dnl ** check for ghc-pkg command