I'm new to Tomcat, so I'm unsure whether there is a configuration to set this. However, I'm using the following in JSP's that seems to solve client caching issues.
1. Place the following in at the start of the JSP
<%
response.setHeader("Cache-Control","no-cache"

; //HTTP 1.1
response.setHeader("Pragma","no-cache"

; //HTTP 1.0
response.setDateHeader ("Expires", 0); //prevents caching at the proxy server
%>
2. Place the following inside the <head> block
<META HTTP-EQUIV="Cache-Control" CONTENT="no-cache">
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">
<META HTTP-EQUIV="Expires" CONTENT="-1">
3. Place the following at the bottom of the file just before the </HEAD>
<head>
<META HTTP-EQUIV="Cache-Control" CONTENT="no-cache">
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">
<META HTTP-EQUIV="Expires" CONTENT="-1">
Of course, if your trying to set the expiring for non-jsp content such as images....