Jack,

I beleive you will need to implement your own table model. The Java tutorial
at http://java.sun.com/docs/books/tutorial/uiswing/components/table.html is
what I read through to get around a similar problem. I created my own table
model and used a custom renderer.

class MyJLabelRenderer extends JLabel implements TableCellRenderer {

   // constructor
   MyJLabelRenderer() {
       this.setHorizontalAlignment(CENTER);
   }

   // returns component to use as renderer
   public Component getTableCellRendererComponent(JTable table, Object
value, boolean isSelected, boolean hasFocus, int row, int col) {
       // could have some other logic in here...
       return this;
   }
}