Fake cron?

[eluser]esra[/eluser]
If you are attempting to design an application that runs on all web servers, using CRON is not a good choice if Windows support is desirable. PHP does not support multiple threads, but methods of simulating multithreaded operations have been developed.

There are a couple of classes on phpclasses.org that simulate multithreading (do a search on 'thread'). I have never used these myself, but the general approach seems useful for handling your needs. You could spin off a new thread to handle background processing operations and build an admin interface to handle scheuled events for those background operations, possibly based on CI's calendar library.