One way to do this is to make use of the little known autorun feature of the command processor. I remembered that this was possible so did a Google search only to be given a link to my own Blog! I'd forgotten about writing this:
You can set an autorun command via the registry at either of these locations according to need:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Command Processor HKEY_CURRENT_USER\SOFTWARE\Microsoft\Command Processor
I use the following setting:
%USERPROFILE%\.profile.cmd
Which runs that cmd file every time I start a command line. In the autorun command you could simply display the output of a text file. In your app, dump some text to the text file, start the command line. You should then empty the text file (don't delete it) so you don't keep getting the prompt.
You could add some further intelligence if needed so that the text file is only displayed for your app.
Of course, you could also change the registry on the fly from your app.