The improvement to the text editor on the Career Portal should make it easier for you to format the text of your jobs. It is a very traditional WYSIWYG (what you see is what you get) editor.
To enter your own HTML code, you can open up the HTML viewer by clicking on the last button on the right of the top of each editable form field. You would then copy and paste your code into the new window and click update. You will then still be on the Add/Edit a Job page, where you will see a preview of how your text will look in a visual view.