Running Scripts and Dialogs

I am trying to set up a bulk exporter for Thea Render to create files for geometry created in Grasshopper. I have hit a problem in trying to export more than a single file. I can run:

RhinoApp.RunScript("_RTExport", false);

to export the file, but this will just use the default name in the RhinoThearos plugin, or pull up a dialog. Adding the dash for:

RhinoApp.RunScript("_-RTExport", false);

does not seem to suppress the dialog. Is there any way using RhinoCommon I can either pass the file name I want to the command, or get into the plugin to change its settings? Sadly the plugin returns null when I call:

Rhino.Plugins.Plugin.Find(Rhino.Plugins.Plugin.IdFromName("RhinoThearos"));

Although just calling IdFromName does give a result, so I am using the right name!