Index: debian/pkgsel.templates
===================================================================
--- debian/pkgsel.templates	(revision 34762)
+++ debian/pkgsel.templates	(working copy)
@@ -26,3 +26,8 @@
 # The text is used at the end of the installation phase while
 # cleaning up pkgsel's stuff
 _Description: Cleaning up...
+
+Template: pkgsel/include-packages
+Type: string
+Description: space-separated list of extra packages to install
+ For preseeding only; not translated.
Index: debian/postinst
===================================================================
--- debian/postinst	(revision 34762)
+++ debian/postinst	(working copy)
@@ -50,7 +50,7 @@
 
 db_progress INFO pkgsel/progress/tasksel
 ret=0
-in-target sh -c "$config tasksel --new-install --debconf-apt-progress='--from 5 --to 95 --logstderr'" || ret=$?
+in-target sh -c "$config tasksel --new-install --debconf-apt-progress='--from 5 --to 90 --logstderr'" || ret=$?
 if [ "$ret" != 0 ]; then
 	# In case packages failed to install, try to clean up.
 	in-target dpkg --configure -a || true
@@ -64,6 +64,25 @@
 	exit $ret
 fi
 
+db_get pkgsel/include-packages
+if [ "$RET" ]; then
+	in-target sh -c "$config debconf-apt-progress --from 90 --to 95 --logstderr -- aptitude -q --without-recommends -y install $RET" || ret=$?
+	if [ "$ret" != 0 ]; then
+		# In case packages failed to install, try to clean up.
+		in-target dpkg --configure -a || true
+
+		# TODO useful error message here (for ret != 30)
+		db_progress INFO pkgsel/progress/cleanup
+		if ! cleanup; then
+			log "cleanup failed"
+		fi
+		db_progress STOP
+		exit $ret
+	fi
+else
+	db_progress STEP 5
+fi
+
 db_progress INFO pkgsel/progress/cleanup
 if ! cleanup; then
 	log "cleanup failed"