ZBEDic supports QCop interprocess messages. To setup QTReader to use zbedic for word lookup, go to Settings->Configuration->Locale and enter 'zbedic' as an application and 'find' as a message name.
To speed up zbedic startup time, you can activate Fast load: long-press zbedic icon in Applications tab, then put a tick at Fast load. Note however that untill zbedic is selected as a Fast load application, it is still running. Therefore you can not uninstall the application or remove CF/SD card if there are any active dictionaries on that card.