You can use the mouse wheel by handling the MouseWheel event and changing ScrollX/Y from there. This event is inherited from the Control class, but some reason it doesn't appear in the VS event list; you must add a handler for it manually.

private void Form1_Load(object sender, System.EventArgs e)
{
  fc.MouseWheel += new   
    MouseEventHandler(fc_MouseWheel);
}

void fc_MouseWheel(object sender, MouseEventArgs args)
{
  FlowChart fcSender = sender as FlowChart;

  float newScrollY = fcSender.ScrollY - args.Delta / 50;
  if (newScrollY > fcSender.DocExtents.Top)
    fcSender.ScrollY = newScrollY;
}

Stoyan