Here is how we did it:
1. From edit page, add a "Custom HTML" to the Tab's Resource Column in the "Customize Page"
2. Then, edit the "Custom HTML" window
3. Add the URL as an iframe, example below to load View ID 515 as a tab
<iframe src='http://orionExample/Orion/SummaryView.aspx?ViewID=515' width='100%' height='1000'></iframe>
4. You will probably have to adjust the height depending on the size of your page.