How to force browser to create a new session in each tab

Hi, we need, in a jsp web application, to open multiple web pages using different http sessions in each tab (like explorer 7 default), in Internet Explorer  8-9 and Firefox.
We would like to emulate the same function that Internet Explorer allow by command line with the parameter "-nomerge" but we do not know if this is possible with a specific html tag, response attribute or cookie to store with particular attributes..

Thanks in advance
Simone