Using a C++ DLL

I have an interesting question here. I am trying to create an interface between a third party application which can make use of C/C++ DLLs, but no interface directly to .NET. What I was hoping to accomplish (not sure if possible though), is create a very basic C++ DLL (not .NET), which the third party application would call directly. This DLL would contain a basic method such as "DoSomething()". Somehow, from my .NET application, I want to "listen" to this DLL and "takeover" the DoSomething() method, and then returning the result back to the DLL, which will in turn return the result back to the calling third party application.

I don't even know if this is possible because I'm sure I would somehow have to get a hold of the memory space of the DLL as initiated by the third party application.

Also, it seems that creating a managed DLL does not work, based on feedback from other individuals who have tried this.

Any help or pointers on this topic would be appreciated.

Probably not on listening a method inside the dll without using hacking readmemory techniques, most certainly possible to incorporate some c++ dll method in vb with dllimport.
It is possible however to listen to the whole c++ application and see when it is instantiated.After that maybe you can call the dll method to see if you get a response but for more on that post on the API forum.