Chrism... I think you're missing the point: Windows does not support unix style permissions. It has its own scheme and quite different "system hooks.</" Hence, unless the docs for your W32 version of perl specifically say that chmod DWIMS on an IIS server, it's extremely UNLIKELY to do so.   See:
http://www.tnsites.com/support/s_CHMOD-tutorial.asp

How to convert CHMOD Commands (Permission Codes) to Windows Permissions
You cannot set CHMOD on a Windows 2003 server since that is a Unix/Linux server command function that does not work on Windows IIS5 servers....

Suggest you read the original (above), or, similarly,
http://www.1planhost.com/support/s_CHMOD-tutorial.asp
and many other ISP explanations (LIGHT APPEARS! ...perhaps even that provided by the relevant ISP?)

Other, perhaps useful discussions appear at:

• http://www.mkssoftware.com/docs/man1/chmod.1.asp
• http://lists.evolt.org/archive/Week-of-Mon-20020930/123647.html
  

  "With command line access you can use attrib, but this won't allow you to add/change account/group access.
  ...
  You probably need to add read/write/modify access the IIS web server account to the target directory."

• http://www.opentechsupport.net/forums/archive/topic/22905-1.html
  (assume garish background, hurts the eyes, but ain't entirely useless.

Hope this helps.