File Manager using wrong file path

I'm working with the File Manager portion of the HTML Editor (in this page, this is independent of the HTML editor).

No matter what I try the file path that is inserted into the database is

/siterootdirectory/imagedirectory/file.ext

That /siterootdirectory/ will make the files invalid once I make this site live. On my testing machine the siterootdirectory will be something like "sitename" but on the live server the root directory will be "public_html"

Even if I set the paths to recall the data to ../siterootdirectory/ it won't work because the siterootdirectory isn't the same name from local to live server.

Please advise how to change this.

I have tried putting the imagedirectory inside the same directory as the page with the file manager upload, I have tried changing all sorts of settings.

From reading the forum it wold appear there is a place to change the "root directory" but I can't find a folder for "HTML Editor" anywhere in my site files.

Using PHP, HTML Editor 3.01. Dreamweaver CS3, Mac OSX. Server is MAMP.

Thank you.