Windows 7 and Internet Explorer 8: no grouping per browser instance?

"To undo grouping:

Right-click the Taskbar, choose Properties, then Taskbar.
Then in the drop-down list titled ""Taskbat buttons"": choose ""Never combine"", then OK."

"You might like: never combine + hide labels
It takes less space than the don't combine option in win7 but it allows you to keep the icons from sticking together. The specific thing you are looking for it probably not possible without a very complicated hack/mod.
Here's a related superuser question: Is there any way to hide taskbar labels and not combine taskbar buttons?
Infact here is a petition to add the functionality you want: http://www.windows7taskforce.com/view/1454"