Hopefully my answer in your other thwack posting Re: Custom Device prompts definition has helped a little here.
However in regard to getting CatTools to send data first to a device, you could also try turning again to the Variations feature.
Take a look at the Pre/Port Login tab. This allows you to tell the device to send specific keystrokes pre login or post login (for example such as Ctrl-C to continue for HP devices).
You can also configure the keystroke to be sent only when a specific message is received.