Change the output

You don't really need additional functionality to override just the format of the output. You can use the msls_output_get-filter if you want to change the format of the generated links to the translations in your blog.

function my_msls_output_get( $url, $link, $current ) {
    return sprintf(
        '<a href="%s" title="%s"%s>%s</a>',
        $url,
        $link->txt,
        ( $current ? ' class="current"' : '' ),
        $link
    );
}
add_filter( 'msls_output_get', 'my_msls_output_get', 10, 3 );

The parameters of the filter are $url (a string which contains the address to a translation), $link (a MslsLink-object) and the boolean $current. The above example transforms the absolute URL in a relative one and adds the css-class 'current' to the link of the current blog.