I don't get what you are trying to do, but if I get you correctly, you would want to link to the DBP compiler, not the launcher (which, as you've already noticed, launches a new instance of the IDE).
Set the link to D:\Dark Basic Professional\Compiler\DBPCompiler.exe instead. As said, I'm not quite sure what you're after, so I can't guarantee you this will work.
Also, why not just use the default DBP editor instead?
Or the new one?
Also, you should be aware that DBC code usually doesn't compile without a few tweaks in DBPro.
Hope that helped