public static void SetNetCodeGroupAccess()
{
    const string userPolicyLevel = "User";
    // Locate the User policy level.
    PolicyLevel level = null;
    System.Collections.IEnumerator ph = 
        System.Security.SecurityManager.PolicyHierarchy();
    while(ph.MoveNext())
    {
        level = (PolicyLevel)ph.Current;
        if( level.Label == userPolicyLevel )
        {
            break;
        }
    }
    if (level.Label != userPolicyLevel)
        throw new ApplicationException("Could not find User policy level.");

    IMembershipCondition membership =
        new UrlMembershipCondition(@"http://www.contoso.com/*");
    NetCodeGroup codeGroup = new NetCodeGroup(membership);
    // Delete default settings.
    codeGroup.ResetConnectAccess();
    // Create an object that represents access to the FTP scheme and default port.
    CodeConnectAccess a1 = new CodeConnectAccess(Uri.UriSchemeFtp, CodeConnectAccess.DefaultPort);
    // Create an object that represents access to the HTTPS scheme and default port.
    CodeConnectAccess a2 = new CodeConnectAccess(Uri.UriSchemeHttps, CodeConnectAccess.DefaultPort);
    // Create an object that represents access to the origin scheme and port.
    CodeConnectAccess a3 = CodeConnectAccess.CreateOriginSchemeAccess(CodeConnectAccess.OriginPort);
    // Add connection access objects to the NetCodeGroup object.
    codeGroup.AddConnectAccess(Uri.UriSchemeHttp, a1);
    codeGroup.AddConnectAccess(Uri.UriSchemeHttp, a2);
    codeGroup.AddConnectAccess(Uri.UriSchemeHttp, a3);
    // Provide name and description information for caspol.exe tool.
    codeGroup.Name = "ContosoHttpCodeGroup";
    codeGroup.Description = "Code originating from contoso.com can connect back using the FTP or HTTPS.";
    // Add the code group to the User policy's root node.
    level.RootCodeGroup.AddChild(codeGroup);
    // Save the changes to the policy level.
    System.Security.SecurityManager.SavePolicy();
}