By default Slidewise adds its own tab to the PowerPoint ribbon. Some people may find this inconvenient, or that it causes problems if you have a lot of tabs. To work around this here are some instructions on how you can add the Slidewise show/hide button to your Home tab to make it easier to access.
Step 1: Open PowerPoint and right-click anywhere on the ribbon - choose Customize the Ribbon...
Step 2: On the right-hand side you should click on Home in the Main Tabs list. Then click New Group button to create a new group to place your Slidewise button into.
Step 3: Click the Rename... button to change the name of your group to Slidewise. You can also now drag the group into the position on the ribbon you want.
Step 4: On the left-hand side now, select Main Tabs from the dropdown at the top. Then find and expand the Slidewise options in the tree. Select Show/Hide and then click Add >> to add the command to the new custom group you have created.
Step 5: Click OK to finish making changes to the ribbon. Note: If you don't want the Slidewise tab to show at all you can simply select the Slidewise group in the right-hand list of the dialog above and click << Remove.
The main Slidewise show/hide button will now appear on your Home tab.