You will need to use the server side script and Response.Write to create dynamic client side script

For example:

Code:
<HTML>
<HEAD>
<SCRIPT language="VBScript">
<!--
<%
Response.Write "Dim strMyValue" & vbCrLf
Response.Write "strMyValue = " & Request.Form("SomeFormData") & vbCrLf
%>
'Then you can use the variable strMyValue in your client side scripts
-->
</SCRIPT>
</HEAD>
.
.
.
You are essentially passing the server side only info to the page by putting it in the HTML stream on page itself.