Hello.

What exactly do you mean? Using the mouse scroll to change from one tab to another or using the mouse scroll to go left and right when there are many tabs open? If it's the former, please check the add-ons gallery: http://addons.mozilla.org/

If it's the later, I believe that's already possible in Firefox. Just put your mouse over the tabs, and use the mouse wheel. It will go left and right as you want, but it won't change tabs.

Dear Morbus,

I mean like using the mouse scroll to change from one tab to another like using the "TabNavIt" add-on.

https://addons.mozilla.org/en-US/firefox/addon/6788/ Looks like that extension hasn't been updated in over a year. Try to contact the developer of that addon to find out if he plans to update it.