LoL, no Martha you wouldn't need a mod for this. And you're correct on how you would go about doing this. You would have to make a chat.asp file and include the html into the chat.asp file. It would look something like this:<!--#INCLUDE FILE="config.asp" -->
<!--#INCLUDE FILE="inc_functions.asp" -->
<!--#INCLUDE FILE="inc_top.asp" -->
<table width="100%" border="0">
<tr>
<td>
<font face="<% =strDefaultFontFace %>" size="<% =strDefaultFontSize %>"><img src="icon_folder_open.gif" border="0"> <a href="default.asp">All Forums</a><br>
<img src="icon_bar.gif" border="0"><img src="icon_folder_open_topic.gif" border="0"> Chat</font>
</td>
</tr>
</table>
Your chat page code goes here
<!--#INCLUDE FILE="inc_footer.asp" -->
That should work. If you don't get it working, you can always send me your chat.htm page and I'll create it for you. 
But I kinda figure you can do this on your own. 