This example shows that all enums, even those defined in the .NET Framework, are automatically cso-ready.

CopyASPX file
<form id="form1" runat="server">
    <div>
        <cso:ObjectGateway ID="objectGateway1" VariableNameOnClientSide="todaysDayOfTheWeek" runat="server" />
    </div>
</form>
<%
CopyCodebehind file
public partial class LearnByExamples_Example05 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        DayOfWeek today = DateTime.Today.DayOfWeek;

        objectGateway1.SourceObject = today;
    }
}
CopyCso-generated enum DefaultNamespace.DayOfWeek
// ****************************************
// CSO Gateway version 0.7.1.0
// Copyright (C) 2010 Pascal Dufresne
// http://csogateway.codeplex.com
// http://csogateway.metaobjects.ca
// ****************************************
// enum DefaultNamespace.DayOfWeek
// dynamically generated from enum: "System.DayOfWeek, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"
// ****************************************


Type.registerNamespace('DefaultNamespace');

DefaultNamespace.DayOfWeek = function(){};
DefaultNamespace.DayOfWeek.prototype = 
{
  Sunday:0,
  Monday:1,
  Tuesday:2,
  Wednesday:3,
  Thursday:4,
  Friday:5,
  Saturday:6
}

DefaultNamespace.DayOfWeek.registerEnum('DefaultNamespace.DayOfWeek');
CopyResult in browser
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head><title>
    Learn by examples #5
</title>
<script type="text/javascript" src="csogateway.axd?import=MicrosoftAjax.js"></script>
<script type="text/javascript" src="csogateway.axd?import=CsoGatewayGlobalFunctions.js"></script>
<script type="text/javascript" src="csogateway.axd?import=((DefaultNamespace.DayOfWeek)(System.DayOfWeek%2c+mscorlib%2c+Version%3d2.0.0.0%2c+Culture%3dneutral%2c+PublicKeyToken%3db77a5c561934e089))"></script>
</head>
<body>

    <form name="form1" method="post" action="Example5.aspx" id="form1">

<div>
<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="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" />
</div>

        <div>
            <script type="text/javascript">var todaysDayOfTheWeek = DefaultNamespace.DayOfWeek.Wednesday;</script>
        </div>
    </form>

</body>
</html>