It is probably better if you don't add it. I have found when using the remote I would occasionally hit the wheel by accident. If you change the activity by accident and hit the power button.... Stereo On instead of TV off.
You would need to reconfigure the power button to jump into a hidden page.

I think you could have the wheel in one direction do a page down and activity change in the opposite spin direction .

A redesign might be necessary.Here is a example.
You could use the Wheel to change the Pages Up and Down in all activities. On the Home Page have a list of just activities. It could be multiple pages. Add a > indicator or button to show there is more pages. The Power Button should Jump to a Hidden Page within the activity or Home Page. When it is hidden it prevents the page form being accessed when using the wheel.

Another example would be to create a New Activity and copy every page wanted to it. Not every page is needed .The number buttons on a Blu-ray player are rarely used. The Power Button could Jump to a Hidden Page within the activity. On the Home Page have a list of activities with this activity listed First. The hard buttons would only work with one device so choose what is used most often. TV volume up-down cable box channel up-down.You could call this activity TV/DEN and have a similar activity for a different room.