Because this is an external script, you need to look for the
documentation on TinyMCE website.
I've spend lot of time customizing TinyMCE, so maybe you can try to use my configuration:
tiny.custom_plugins
style,advimage,advlink,modxlink,searchreplace,print,contextmenu,paste,fullscreen,noneditable,table,advlink,iespell,inlinepopups,media,directionality,xhtmlxtras,template
tiny.editor_theme
tiny.skin
tiny.custom_buttons1
newdocument,|,bold,italic,underline,forecolor,backcolor,|,justifyleft,justifycenter,justifyright,justifyfull,|,bullist,numlist,|,modxlink,unlink,anchor,image,iespell,media,|,pastetext,pasteword,code,template,|,fullscreen
tiny.custom_buttons2
search,|,strikethrough,outdent,indent,blockquote,|,sub,sup,|,styleselect,formatselect,fontselect,fontsizeselect
tiny.custom_buttons3
tablecontrols,|,removeformat,visualaid,|,undo,redo,|,print,|,ltr,rtl,|,styleprops
tiny.css_selectors
HERE YOU CAN PUT CSS CLASSES