OK, what you could do is this:
1. Go to PageLines > Drag and Drop and clone the Features Slider section in your header template, so that you have two.
2. Now on the cloned features section, click the options button and check hide by default.
3. Now go to Page Options > Page Setup > Category Template and in the Header area of Individual Page Section Control, hide the default Feature Slider and use then check to show the one you cloned that was set to hide by default.
So now you have you just replaced your default Feature Slider section with the cloned one but this will only show on your category page(s).
Now whilst still on Page Options > Category template, click on the Features Sections settings tab and then configure your Feature settings. In the "Select Feature Post Source (Optional - Defaults to Custom Post Type)" select the Post Category option.
This should be work for you!