How to enable scroll wheel on plugins on other hosts

I have question about scroll wheel on plugin. Hopefully someone could shed some light on it. I have a VST2.4 Host(MiniVst host). And I have loaded some plugins and it works well. But I cannot support mouse scroll wheel on plugins, I can only change parameters on plugin panel with press-move. And I find it really can change with scroll wheel with FL Studio. So I think these plugins support scroll wheel, I wonder how to enable this function? Is there any interface to enable it in VST2.4?