There is a cumbersome work around for tasks that would take too long to be possible to do in one sitting, and that is to split the task into several steps, such a log->Initial Foo->Halfway Foo->Partial Foo->Foo. That's definitely not elegant, though. Another work around is to require X Bar items as input for a Baz item, and each Bar item takes a possible amount of time (it's essentially the same work around, but with a nicer coat of paint).
Making it possible to interrupt/resume more tasks will be developed eventually, but it remains to be seen if that extends to modding (and before that, of course, the interrupt/resume extension will have to be implemented, which may not be a near term goal).