Should be able to override the AbsolutePosition and the Offset of the connector. Should be able to specify absolute position manually, not only relative. Should be able to provide template for its visual representation. Fixed in LIB version: 2014.2.0914
The RadDiagramConnector has a virtual method - CalculateRelativePosition which you can use to customize its position. You can see this in our CustomConnectors SDK demo: https://github.com/telerik/xaml-sdk/tree/master/Diagram