Setting Security Permissions on Shared folders

Hello,

No bones about it, I am a newb and looking for an assist.

I am working to create a PS script that will set share permissions for a roaming profile folder as per http://technet.microsoft.com/en-us/library/cc757013%28WS.10%29.aspx. 

The difficulty I am having is that I am not finding success limiting the List Folders/Read Data and Create Folders/Append data toThis folder only.

I am working with a shared directly called UserProfiles.  I am attempting the items below and failing (this of course after failing to create the shared folder in the first place!, one thing at a time).

Seems to me that I am missing the mark on the Inheritance and Propagation flags.  I have attempted swapping them out, but no love.  I want to match the security recommendations referenced in the MS article, but want to do it using Powershell.  Is this possible?

$acl - get-acl C:\UserProfiles

$p1 = "Demo\domain users", "ListDirectory", "none", "NoPropagateInherit", "allow"

$r1 = new-object system.security.accesscontrol.filesystemaccessrule $p1

$acl.addaccessrule($r1)

$acl | set-acl c:\UserProfiles