Here is the patch I've used for dblatex.

You can download it at http://www.davidgis.fr/download/patch-dblatex.patch. Here is the content

--- postgis-svn/configure.ac	2008-09-11 14:18:37.000000000 +0200
+++ postgis-svn-new/configure.ac	2008-09-26 12:12:24.000000000 +0200
@@ -70,9 +70,9 @@
 dnl Search for db2pdf which is required for building PDF documentation
 dnl
 
-AC_PATH_PROG([DB2PDF], [db2pdf], [])
-if test "x$DB2PDF" = "x"; then
-	AC_MSG_WARN([db2pdf is not installed so PDF documentation cannot be built])
+AC_PATH_PROG([DBLATEX], [dblatex], [])
+if test "x$DBLATEX" = "x"; then
+	AC_MSG_WARN([dblatex is not installed so PDF documentation cannot be built])
 fi
 
 
--- postgis-svn/doc/Makefile.in	2008-09-11 14:18:37.000000000 +0200
+++ postgis-svn-new/doc/Makefile.in	2008-09-26 12:26:41.000000000 +0200
@@ -30,8 +30,8 @@
 HTML_DOCBOOK_XSL=$(XSLBASE)/html/docbook.xsl
 CHUNK_HTML_DOCBOOK_XSL=$(XSLBASE)/html/chunk.xsl
 
-# OpenJade's db2pdf script for PDF generation from DocBook
-DB2PDF = @DB2PDF@
+# DBLATEX for PDF generation from DocBook
+DBLATEX = @DBLATEX@
 
 # Directories for documentation and man pages
 PGSQL_DOCDIR=@PGSQL_DOCDIR@
@@ -66,12 +66,14 @@
 		$<
 
 postgis.pdf: postgis-out.xml
-	@if test x"$(DB2PDF)" = x; then \
-	   echo "Error: db2pdf not found, can't build posgis.pdf"; \
-	   echo "       try installing docbook-utils package and then re-run configure"; \
+	@if test x"$(DBLATEX)" = x; then \
+	   echo "Error: dblatex not found, can't build posgis.pdf"; \
+	   echo "       try installing dblatex package from dblatex.sourcegforge.net nd then re-run configure"; \
 	   false; \
 	else \
-	   $(DB2PDF) $< && mv postgis-out.pdf postgis.pdf; \
+	   cp reference.xml reference.xml.orig; cat reference.xml.orig |sed -e "s:term:listitem:g" > reference.xml;\
+	   $(DBLATEX) -T native -t pdf -o postgis.pdf -I "$(PWD)/html" $<; \
+	   rm -f reference.xml.orig;\
 	fi
 
 clean:

In order to patching

wget http://www.postgis.org/postgis-svn.tar.gz;
tar xzf postgis-svn.tar.gz;
wget http://www.davidgis.fr/download/patch-dblatex.patch;
patch -p0 < patch-dblatex.patch