match element name in web.config transformation

In case there are those that would like to change all attributes here it is

<sessionState xdt:Transform="SetAttributes" xdt:Locator="XPath(/configuration/system.web/sessionState)" 
                mode="SQLServer"
                stateConnectionString="tcpip=1234.00" 
                sqlConnectionString="myConnection"
                cookieless="false" 
                timeout="2000"  />

this should work:

<sessionState timeout="2000" 
 xdt:Transform="SetAttributes(timeout)">
</sessionState>