How to add a WYSIWYG editor to Magento custom options

Im trying to implement a wysiwyg editor under text-option in Magentos custom options, but am failing there. I have already searched for several components, but can't get it together though.

I want that editor to appear in the field where the WYSIWYG Value-textarea is right now.

Other source either don't go into detail or aren't working for 1.9.1.

What I have so far: [WR is companyname and EPO is my module]

I've found this snippet, which is used to place a wysiwyg editor on a cms page within a _prepareForm function:

<?php
    if (Mage::getSingleton('cms/wysiwyg_config')->isEnabled() && ($block = $this->getLayout()->getBlock('head'))) {
        $block->setCanLoadTinyMce(true);
    }

    $form = new Varien_Data_Form(array(
        'id' => 'edit_form',
        'action' => $this->getUrl('*/*/save'),
        'method' => 'post'
    ));
    $fieldset = $form->addFieldset('base_fieldset', array(
        'legend' => Mage::helper('wr_epo')->__("Some Information"),
        'class' => 'fieldset-wide',
    ));
    $wysiwygConfig = Mage::getSingleton('cms/wysiwyg_config');
    $fieldset->addField('description', 'editor', array(
        'name' => 'description',
        'label' => Mage::helper('wr_epo')->__('Description'),
        'title' => Mage::helper('wr_epo')->__('Description'),
        'style' => 'height: 600px;',
        'wysiwyg' => true,
        'required' => false,
        'config' => $wysiwygConfig
    ));?>

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