As a start you can read this blog:
It is not for the RadPanelBar but the principle is the same. Also this is WPF so you don't need custom project. Just create new WPF project in blend add reference to our assemblies and drop RadPanelBar in the design area. After that right click and edit the control template.
Let me know if need more help.
All the best,
the Telerik team
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