Redirect from non-existent URL

Plone version 4.3.3

Our old site used mod_userdir to permit users to provide content. These 
no longer exist on my Plone site, so our outside users are visiting 
places like <...>/~user/MyCoolProgram and getting "does not seem to 
exist". I tried creating a "~user" folder in my root, but this got 
translated to "user".

How would I set up a redirect to capture requests for "~user/something" 
and direct it to an existing page on my shiny new Plone site?

Thanks,

-- 
Chuck Theobald
System Administrator
The Robert and Beverly Lewis Center for Neuroimaging
University of Oregon
P: 541-346-0343
F: 541-346-0345


------------------------------------------------------------------------------