Replace get_the_title and the_exerpt with custom arrays

You could use an array of arrays to hold the custom titles and excerpts keyed to the post IDs. In this example, 11, 22, 33, 44, 55, 66, 77, 88 and 99 are sample post IDs.

$slides = array(
    11 => array(
        'title'   => 'Custom title 1',
        'excerpt' => 'Custom excerpt 1',
    ),
    22 => array(
        'title'   => 'Custom title 2',
        'excerpt' => 'Custom excerpt 2',
    ),
    33 => array(
        'title'   => 'Custom title 3',
        'excerpt' => 'Custom excerpt 3',
    ),
    44 => array(
        'title'   => 'Custom title 4',
        'excerpt' => 'Custom excerpt 4',
    ),
    55 => array(
        'title'   => 'Custom title 5',
        'excerpt' => 'Custom excerpt 5',
    ),
    66 => array(
        'title'   => 'Custom title 6',
        'excerpt' => 'Custom excerpt 6',
    ),
    77 => array(
        'title'   => 'Custom title 7',
        'excerpt' => 'Custom excerpt 7',
    ),
    88 => array(
        'title'   => 'Custom title 8',
        'excerpt' => 'Custom excerpt 8',
    ),
    99 => array(
        'title'   => 'Custom title 9',
        'excerpt' => 'Custom excerpt 9',
    ),
);

Instead of using get_the_title() use $slides[$post->ID]['title'].
Instead of the_excerpt() use echo $slides[$post->ID]['excerpt'].