How do I place a dynamic shopping cart into the header (not just a sidebar widget)

[MarketPress Plugin Installed on - Couldn't get the menus on the form to cooperate]

We like having your shopping cart widget to place in our various sidebars. However, there are times when having a Sidebar on a page doesn't fit our design or layout needs, but we need the Shopping Cart to always be visible.

Is there a way to get a dynamic shopping cart icon that updates when items are added in other areas of the website (such as the header; i.e. Amazon, etc.).