In this case, the security measure is provided by the web applications, such as JTS, CCM and etc. If you want the resources to be safeguarded by such a security measure, the resources have to be within the context of the web application. If the resources are located as described above, they are clearly out of the context of any web applications running on the Tomcat server, and you will need to rely on Tomcat's own security management, which is most likely different from CLM and not what you want.
To get something similar to the jazz.net widget you posted, you probably need to do something like this (images and other files are packaged together in the viewlet).
https://www.ibm.com/developerworks/rational/library/10/createdashboardviewletsinrationalteamconcert/index.html