you would need to use Data Bridge to be able to edit the HTML Editor instance on the admin/contents_insert.php and contents_update.php.
When editing the HTML Editor instance, edit the preset then go to the styles tab to attach your style sheet
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.