We don't have a -k option for tar(1) so use pax(1) with its -k option.

x11/e17/e/Makefile

@@ -1,8 +1,8 @@
-# $OpenBSD: Makefile,v 1.5 2007/12/03 11:36:28 bernd Exp $
+# $OpenBSD: Makefile,v 1.6 2007/12/04 17:43:15 bernd Exp $
 
 COMMENT=	the enlightened window manager
 DISTNAME=	e-20071107
-PKGNAME=	${DISTNAME}p1
+PKGNAME=	${DISTNAME}p2
 
 # BSD
 PERMIT_PACKAGE_CDROM=	Yes

x11/e17/e/patches/patch-src_bin_e_main_c

@@ -0,0 +1,32 @@
+$OpenBSD: patch-src_bin_e_main_c,v 1.1 2007/12/04 17:43:15 bernd Exp $
+
+The OpenBSD tar(1) doesn't have a -k option to preserve existing files.
+Use pax(1) with its -k option.
+
+--- src/bin/e_main.c.orig	Mon Dec  3 13:59:16 2007
++++ src/bin/e_main.c	Mon Dec  3 13:59:48 2007
+@@ -1088,13 +1088,13 @@ _e_main_dirs_init(void)
+      {
+ 	snprintf(buf, sizeof(buf), 
+ 		 "gzip -d -c < %s/data/other/desktop_files.tar.gz | "
+-		 "(cd %s/applications/ ; tar -xkf -)", 
++		 "(cd %s/applications/ ; /bin/pax -rk)", 
+ 		 e_prefix_data_get(),
+ 		 efreet_data_home_get());
+ 	system(buf);
+ 	snprintf(buf, sizeof(buf), 
+ 		 "gzip -d -c < %s/data/other/desktop_order.tar.gz | "
+-		 "(cd %s/.e/e/ ; tar -xkf -)", 
++		 "(cd %s/.e/e/ ; /bin/pax -rk)", 
+ 		 e_prefix_data_get(),
+ 		 homedir);
+ 	system(buf);
+@@ -1105,7 +1105,7 @@ _e_main_dirs_init(void)
+      {
+ 	snprintf(buf, sizeof(buf), 
+ 		 "gzip -d -c < %s/data/other/efm_favorites.tar.gz | "
+-		 "(cd %s/.e/e/ ; tar -xkf -)", 
++		 "(cd %s/.e/e/ ; /bin/pax -rk)", 
+ 		 e_prefix_data_get(),
+ 		 homedir);
+ 	system(buf);