If I understand you right you want to use the convert dialog to simultae these mentioned actions.
You have to do it the other way:
Create an action group (several actions that are executed with one click) and add an action to this goup that is equivalent to the action of the convert-menue. The items of the convert-menue are only predefined actions with a preview and you can do the same and very much more if you define actions with the action-menue.
Action:
Format value:
Field: _filename
Format String: %artist% - %title%