Read the FAQ linked on Macaroon's download page, specifically under the section about creating a vehicle/possession bar. It's extremely simple to add a vehicle/possess "page" to an existing bar, though you will probably have to reconfigure the actions on the bar, since adding a new state will alter the page ordering.
"reconfigure the actions bar since adding a new state will alter the page ordering"
Im sure this is quite simple to you but if its not to much bother could you explain that bit alittle more?
If you use custom state definitions (the "Custom" checkbox) adding the possess state will change the order of pages, and since buttons are linked only to the page number, not the page state, you'll now have an extra page and bump all of the rest of your pages down the line, and your buttons will all be on the "previous" page from where they were before. But if you set up paging using the checkboxes, this doesn't apply to you at all and you can just follow the directions in the FAQ.