$ perl -e 'BEGIN{use File::Path qw(make_path)} make_path("foo/bar", { mode => 02750 })' 
$ ls -lh
total 4.0K
drwxr-x--- 3 hena hena 4.0K 2012-04-27 12:14 foo
$ mkdir faa
$ chmod 2750 faa
$ ls -lh
total 8.0K
drwxr-s--- 2 hena hena 4.0K 2012-04-27 12:15 faa
drwxr-x--- 3 hena hena 4.0K 2012-04-27 12:14 foo