Overriding the Default "Activities" Tab

This may be totally obvious, but how can I override the default activities tab? I get an error message if I try to create the VF page like so:

<apex:page standardController="<strong>Task</strong>" recordsetvar="c" extensions="skuid.Redirects"
action="{!redirect}?objectType=Task&amp;actionType=<strong>Tab</strong>">

And I can't see a place in Tasks Buttons, Actions, Links to set the override either.

Thanks!

If memory recalls, Task is a special object (Activity) and does not have a Tab.

Thanks Irvin.

You may be correct, although there is a default Activities tab, at least in my org. I guess I can always create a custom VF tab and replace the default one though. 

That has been our standard practice.  New VF tab for Tasks…