This type of columns cannot be edited in MS Access 2007, even when I created a Form in MS Access 2007, I cannot find a HTML editor control to put on the form and bind to this kind of columns.
Columns of type Publishing HTML is used to store HTML content displayed as part of a web page in a SharePoint list field. The content in this type of field should be edited by web page end user in browser with the field control put on the web page. Developers and designers are responsible for adding field controls to the page layout ASPX file by using a tool such as Microsoft Office SharePoint Designer 2007 or by editing the ASPX file deployed by using a Feature.
So, you should not change the column type to edit it in MS Access 2007.
For more information on this data type, please refer to: http://msdn.microsoft.com/en-us/library/dd571480.aspx and http://blogs.msdn.com/ecm/archive/2008/10/09/publishing-sites-field-controls-or-web-parts-that-is-the-question.aspx