Finally, I've been found the way to add nodes!!!

Here you are the rigth code:

    Procedure DoAddNodo
        Handle hoFlowGraphPaintManager hoFlowGraphPage hoNode hoFlowGraphNodes
        Variant vActivePage vPaintManager vNodes vAddResourceNode
        Get ComActivePage     of oComFlowGraph to vActivePage
        Get ComPaintManager of oComFlowGraph to vPaintManager
        Get Create (RefClass(cComFlowGraphPaintManager)) to hoFlowGraphPaintManager
        Set pvComObject of hoFlowGraphPaintManager to vPaintManager

        Set ComConnectorType            of hoFlowGraphPaintManager to OLExtpFlowGraphConnectorStraight  
        Set ComConnectionColor          of hoFlowGraphPaintManager to clRed 
        Set ComNodeBackgroundColor  of hoFlowGraphPaintManager to clWhite         
        Get Create (RefClass(cComFlowGraphPage)) to hoFlowGraphPage
        Set pvComObject  of hoFlowGraphPage to vActivePage        
        Get ComNodes     of hoFlowGraphPage to vNodes                   
        Get Create (RefClass(cComFlowGraphNodeCustom)) to hoNode        
        Get Create (RefClass(cComFlowGraphNodes)) to hoFlowGraphNodes
        Set pvComObject of hoFlowGraphNodes to vNodes              

        Get ComAddResourceNode of hoFlowGraphNodes OLExtpFlowGraphShapeRectangleRounded to vAddResourceNode
        Set pvComObject of hoNode to vAddResourceNode                 
        Set ComCaptionPosition of hoNode to OLExtpFlowGraphCustomNodeCaptionCenter
        Set ComLocationX         of hoNode to 1
        Set ComLocationY         of hoNode to 1   
        Set ComHeight             of hoNode to 30
        Set ComWidth              of hoNode to 200
        Set ComCaption           of hoNode to "Nuevo Nodo"                     
        Set ComColor              of hoNode to clWhite                        
        Get ComAddCustomNode of hoFlowGraphNodes to vAddResourceNode               

        Send ComRedrawControl of oComFlowGraph 
        Send Destroy of hoFlowGraphNodes
        Send Destroy of hoNode
        Send Destroy of hoFlowGraphPage
        Send Destroy of hoFlowGraphPaintManager
Now, all I have to do is to find a way to distinguish between node and connector!!