What about date-independent planning?
 

Does OmniPlan have the ability to plan events and processes without connecting them to specific dates?

A number of projects require us to plan a process in the abstract. A manufacturing assembly line, for instance, requires a complex cycle of carefully timed operations with durations of hours, minutes, seconds or even fractions of a second; but the date and time of day are irrelevant to the process.

I'd love to be able to cut loose from the calendar and plan an event in relative, rather than absolute, time. The process should begin at 00:00:00 (hours:minutes:seconds), and include tasks of fixed duration (00:03:10), and yield a total time for the complete chain of events (05:23:17).

Is it possible to do this without linking each task to a specific date or time of day?

If you set the start date for the project in the Inspector to Undetermined date, and set your work day to be 24 hours long (be sure to adjust the effort conversion factors to reflect the longer day), I think you'll find that you can do that reasonably well.