iNik, sorry we missed this the first time through, but we got a customer email asking for something along these lines today. That led us back to this thread and also led us to discover Don Southard's OmniFocusCLI
, which may save you some work. It's a shell script that creates OmniFocus tasks and can be used with Alfred, Hazel, etc.
(The intended use of the URL handler is pretty narrow - it's meant to pass the necessary information when there's no other way to do so than as a URL. We'd recommend using it as an input to the other automation methods that let you control OmniFocus' behavior.)