Now that pkg create can directly accept both a file and a plist in command line,

directly use it

Makefile.inc1

@@ -1214,24 +1214,22 @@ create-world-packages:
 		${DESTDIR}/METALOG
 	@for plist in ${DESTDIR}/*.plist; do \
 		plist=$${plist##*/} ; \
-		test -d ${SRCDIR}/release/packages/$${plist%.plist} || \
+		test -f ${SRCDIR}/release/packages/$${plist%.plist}.ucl || \
 			( echo "Unkown package FreeBSD-$${plist%.plist}" ; false ) ; \
 	done
 	@for plist in ${DESTDIR}/*.plist; do \
 		plist=$${plist##*/} ; \
 		pkgname=$${plist%.plist} ; \
-		rm -rf ${DESTDIR}/$${pkgname}-manifestdir ; \
-		cp -r ${SRCDIR}/release/packages/$${pkgname} \
-			${DESTDIR}/$${pkgname}-manifestdir ; \
-		sed -i '' -e "s/%VERSION%/${PKG_VERSION}/" \
+		sed -e "s/%VERSION%/${PKG_VERSION}/" \
 			-e "s/%PKGNAME%/$${pkgname}/" \
 			-e "s/%COMMENT%/Generic comment for $${pkgname}/" \
 			-e "s/%DESC%/Generic description for $${pkgname}/" \
-			${DESTDIR}/$${pkgname}-manifestdir/+MANIFEST ; \
+			${SRCDIR}/release/packages/$${pkgname}.ucl \
+			> ${DESTDIR}/$${pkgname}.ucl ; \
 		awk -F\" '/name/ { printf("===> Creating %s-", $$2) } /version/ {print $$2 }' \
 			${DESTDIR}/$${pkgname}-manifestdir/+MANIFEST ; \
 		pkg -o ABI_FILE=${DESTDIR}/bin/sh \
-			create -m ${DESTDIR}/$${pkgname}-manifestdir \
+			create -M ${DESTDIR}/$${pkgname}.ucl \
 			-p ${DESTDIR}/$${pkgname}.plist \
 			-r ${DESTDIR} -o ${DESTDIR} ; \
 	done

release/packages/kernel.ucl

@@ -11,3 +11,6 @@ licenses = [ BSD2CLAUSE ]
 desc = <<EOD
 %DESC%
 EOD
+post-install = <<EOD
+/usr/sbin/kldxref /boot/kernel
+EOD

release/packages/ssh.ucl

@@ -0,0 +1,13 @@
+name = "FreeBSD-ssh"
+origin = "base"
+version = "%VERSION%"
+comment = "Secure SHell"
+categories = [ base ]
+maintainer = "re@FreeBSD.org"
+www = "http://www.FreeBSD.org"
+prefix = "/"
+licenselogic = "single"
+licenses = [ ISCL ]
+desc = <<EOD
+TODO
+EOD