I think you might be over-thinking this and making it a lot more complicated than it has to be.
Start with a HoverBox stack in the page. Set the the link address of the HoverBox to simply # and give it a class attribute of something like myTopBox (you don’t want the HoverBox to link to another page and the class attribute is used as a custom trigger for the desired TopBox stack on the page). HoverBox is now your TopBox trigger. Nothing else to configure in here.
Go ahead and add a TopBox stack to the page if you’ve not done so yet. You’ll want to set the TopBox Trigger to Custom and make sure the entry against the Custom Trigger setting matches what you gave HoverBox.
The key towards getting this to work is to ensure the custom trigger (e.g. myTopBox) is the same for both the TopBox and the HoverBox. Because this is a class attribute, the custom trigger used in TopBox starts with a full stop. Other than that, they’re both identical. Standard web development practices. The flexibility exists to use ID’s or other selectors if you choose too.
Keep HoverBox outside of TopBox. Otherwise (as per my previous post) the link layer used for your Topbox trigger will smother the HoverBox stack nested below. The HoverBox stack will not then be able to receive mouse focus and the rollover effects will not work. Use the custom triggers option instead within TopBox. It’s exceptionally powerful and opens up the ability to use TopBox in various configurations, while avoiding conflicts with other stack elements.
File download: https://dl.dropboxusercontent.com/u/422052/HoverBox-TopBox-Combo.zip
[Download link valid for 12 hours only - requires HoverBox, TopBox and Blank theme]