I don't think you can do that with VB Dll. In general you could use JNI (which is a big hassle and unstable) to call C++ methods from Java. I don't think it works with VB. One thought though. If you are developing code that relies on VB dll then you are not interested in platform independence and either VB or VC++ might work better for you than Java.
I’ve looked at a lot of different solutions, and in my humble opinion Aspose is the way to go. Here’s the link: http://aspose.com
subject: How Do i call The Methods of DLL File Created in VB into Java file