Does anyone have any clever (easy? automatic?) ways to build large quantities of page redirects?
If I understood the problem, I'd suggest you to create/generate an XML file digestible by the Special:Import page. The format is easy for both creating it manually from scratch or generation through an external script.
Have a look at this page for more info on the format:
http://meta.wikimedia.org/wiki/Export#Export_format
(import and export format are identical)
Ciao!
Manu