Is there a way to define wp_editor() with custom tinyMCE buttons?

I've noticed the wp_editor function reference mentions that one of the $settings arguments can be tinymce (array) (optional) Load TinyMCE, can be used to pass settings directly to TinyMCE using an array().

My page uses a number of different instances and I'd like to add certain buttons to certain instances.

For example,

Instance #1 : Standard buttons
Instance #2 : bold, italic, ul + (custom) pH, temp
Instance #3 : bold, italic, ul + (custom) min_size, max_size

Does anyone know how I'd go about doing this if I've already registered the buttons as tinyMCE plugins as per this tutorial?

Thanks in advance,

Is there a way to define wp_editor() with custom tinyMCE buttons?

I've noticed the wp_editor function reference mentions that one of the $settings arguments can be tinymce (array) (optional) Load TinyMCE, can be used to pass settings directly to TinyMCE using an array().

My page uses a number of different instances and I'd like to add certain buttons to certain instances.

For example,

Instance #1 : Standard buttons
Instance #2 : bold, italic, ul + (custom) pH, temp
Instance #3 : bold, italic, ul + (custom) min_size, max_size

Does anyone know how I'd go about doing this if I've already registered the buttons as tinyMCE plugins as per this tutorial?

EDIT

Here's the code I'm using in my plugin file to get this working:

function add_SF_buttons() {
    if ( ! current_user_can('edit_posts') && ! current_user_can('edit_pages') )
        return;
    if ( get_user_option('rich_editing') == 'true') {
        add_filter('mce_external_plugins', 'add_SF_buttons_plugins');
    }
}

function add_SF_buttons_plugins($plugin_array) {
    $plugin_array['pH'] = $this->plugin_url . '/js/tinymce_buttons/pH.js';
    $plugin_array['pH_min'] = $this->plugin_url . '/js/tinymce_buttons/pH_min.js';
    $plugin_array['pH_max'] = $this->plugin_url . '/js/tinymce_buttons/pH_max.js';
    return $plugin_array;
}

if (isset($SpeciesProfile)) {
    add_action( 'init' , array (&$SpeciesProfile, 'register_species' ));
    add_action( 'init' , array( &$SpeciesProfile, 'register_species_taxonomies' ));
    
    add_action( 'init', array (&$SpeciesProfile, 'add_SF_buttons' ));
}

<?php wp_editor( $distribution, 'distribution', array( 'theme_advanced_buttons1' => 'bold, italic, ul, pH, pH_min', "media_buttons" => false, "textarea_rows" => 8, "tabindex" => 4 ) ); ?>

Unfortunately, this doesn't work - the above editor simply displays the same buttons as every other instance on the page.

Thanks in advance,