This patch prevents rsync from changing the creation date on the root of a volume. On HFS+, the root inode is always 2, as defined in hfs/hfs_format.h:

kHFSRootFolderID		= 2,	/* Folder ID of the root folder */

So before calling set_create_time(), we verify from the existing stat struct that the inode of the current file is not 2.

diff -Naur rsync-3.0.7_orig/rsync.c rsync-3.0.7/rsync.c
--- rsync-3.0.7_orig/rsync.c	2010-09-16 10:49:54.000000000 -0500
+++ rsync-3.0.7/rsync.c	2010-09-16 10:50:43.000000000 -0500
@@ -480,6 +480,7 @@
 		if (sxp->crtime == 0)
 			sxp->crtime = get_create_time(fname);
 		if (cmp_time(sxp->crtime, file_crtime) != 0
+		 && sxp->st.st_ino != 2 // Don't set the creation date on the root folder of an HFS+ volume
 		 && set_create_time(fname, file_crtime) == 0)
 			updated = 1;
 	}