Hi AJL,
I haven't done this before, but give this a try, it should work. Create a SUDialog with the background of the splashscreen you want. Then call the LV code through ActiveX from the SUDialog. When the LabVIEW VI starts up, have it create an empty file on pre-specified path. The SUDialog will poll that file path until it exists, then execute WndShow("SHELL", "MINIMIZE").
I'm pretty sure if you try to communicate back to DIAdem from LabVIEW that the SUDialog will have reserved DIAdem's OLE Automation Server, so that any LabVIEW commands won't execute until after the SUDialog ends. That's why the low-tech file polling.
Something like that ought to work,
Brad Turpin
DIAdem Product Support Engineer
National Instruments