disappearing web apps

When I install my app using the application manager, I've been specifying a context and a directory URL. everything works until I start Tomcat the next time, then the application is not even listed, not alone not started.
I thought that this disappearing app problem might be because I didn't have a WEB-INF/web.xml file so I supplied one. After I did that, a web-app was started automatically when Tomcat was started but at a context path of the document path of the application, not the /context path I wanted.
It appears that it is impossible to install an application with a context path different than the document root and have that application exist beyond that life of the Tomcat container. process.
Please, somebody help me with this. Its driving me crazy and I'm thinking of running to JRun.
P.S. I tried installing the app specifying a context path, a web.xml and a directory URL. That worked but it ignored by context path entry. The documentation says that it will ignore it, and that the system administrator will take care of it later, but it doesn't describe how the system administrator is supposed to do that.