Unfortunately, it's not possible. The only importing option is currently the "Import/Export templates" feature that accepts specially formatted TXT files.
You can see how it works in this short video: https://www.youtube.com/watch?v=_Rl_CLGY_3o
And refer to this thread: http://todoist.com/Support/showQuestion/4269/ for details about the template format we use.
Vineesh Kumar on Apr 12, 2013 - 08:44
Thanks for the update.
Is this in the roadmap?
Would certainly believe this to be a in-demand requirement.
Thanks and Warm Regards,
We're currently allowing a one-way calendar export feature via iCal. We may consider enabling a two-way synchronization, we're not sure about direct import, though. We're currently working on our own calendar view within Todoist which will allow you to manage all your tasks in Todoist and use it as a calendar :)
Vineesh Kumar on Apr 12, 2013 - 08:52
Though the issue is that many people & sites still offer an ICS file for setting up their meeting schedules which integrates well with Google Cal, but just doesn't play with Todoist without the effort of re-entering that data.
Anyway, thanks a ton for your support!