You can handle the KeyDown event on the GridControl, check the keys pressed and move the current cell up.
void Grid_KeyDown(object sender, KeyEventArgs e)
{
if ((e.KeyCode & Keys.Enter) == Keys.Enter && e.Modifiers == Keys.Shift)
{
grid.CurrentCell.Move(GridDirectionType.Up, 1, false);
e.Handled = true;
}
}