Working with tabs/accordions? Want to add buttons to let the user go back and forth to different pages? You can do this by simply setting the selectedIndex on the tab/accordion. Assuming your accordion has the name accordion1, this button will send you to page 1.
Obviously if you want to go from page 3 to page 2, selectedIndex would be set to 1. You could probably rewrite this to sniff the current active page and just set it to a value one less.
In fact, I shouldn't be so lazy. Here is the "proper" version:
Obviously a "Next" button would be slightly different.