Using oleexp for CoreAudio. Some Help and Advice needed please.

I am exploring data capture with IAudioClient and IAudioCaptureClient (working in Exclusive Mode) using VB6. I would like to do some essential buffer handling in a CallBack Event using IAudioClient.SetEventHandle.

I just can not work out how to do this, is it even possible in VB6???? What do I supply as the long EventHandle required in SetEventHandle? And where does my buffer handling code go????
In the past I have used "addressof" to supply a callback subroutine in a code module, but I think that a CallBack Event is a very different thing.

I am hoping that the BufferFull event can be executed in a high priority callback so that it can execute even if my code is otherwise busy. If its all about sending a windows message to a Form then this is likely no good as VB6 message handling stops when my code is busy.