Got this up and running on lettuce.
URLs like this: http://lettuce.tapor.uvic.ca/cocoon/journals/scancan/ and this: http://lettuce.tapor.uvic.ca/cocoon/projects/scancan/ are now working.

So, to create a cocoon-based app, just create a {homedir}/webapps/ directory on a tapor host (as in home1t/your-username/webapps/) with your application in it (the root of webapps needs to have a sitemap in it, remember. If you have more than one webapp you'll obviously need a sitemap that provides pipelines to your apps). Once done, your app will available at http://lettuce.tapor.uvic.ca/cocoon/projects/{your-username}/ - remember the final slash, it's important!