I have been using separate classes/scripts for my custom metaboxes creation. The two scripts I have been using are the one from deluxeblogtips and the one from jaredatch over on github.
My review custom post type does not support the WP-editor (‘supports’ => array( ‘title’, ‘thumbnail’, ‘excerpt’, ‘author’, ‘comments’ ),), I am using a TwentyTen Child theme and I have implemented 11 custom meta boxes of which 6 use the TinyMCE editor.
In WP 3.1.4 everything went well, but after upgrading to WP 3.2 the WYSIWYG editor has gone missing. Both scripts, same results (or lack thereof I should say).