Multiple applications under Mongrel using routes

My shared host limits the number of mongrel instances I can run, so I'd
like to run multiple applications in one mongrel instance. For
  actually ends up running application in /home/rails/app1/
  actually ends up running application in /home/rails/app2/

I understand how to do this if I have access to the Apache and mongrel
configurations, but I do not have such access. The only things I have
access to change are the files within my application(s).

Is there a way to do it using routes and maybe some sort of "wrapper"
application, ie maybe with a folder structure like this:


Perhaps using Dan Webb's Request Routing plug-in would assist?