First up, the official recommendation of placing the actual <hr> tags in your Word Documents is crap, pure and simple. It doesn't recognize them in normal documents. It recognizes them in the DocX format (the Word 2007 format intended to make everyone's life more painful), however it will double and/or triple space your paragraphs, which quite frankly looks just about as lovely as their little horizontal line. So I wouldn't try either of these methods.
(Please note, these are just what I've found that works. I tried about fourteen methods, and these were the easiest for me. Also, I'm sure many of you are plenty tech savvy, but I wrote the directions in case someone has the technical expertise of most of the customers I talk with at work do.)
So then, if you have only used FFnet to upload your stories, but you still have the original Word Document, here's what I would do.
Upload like normal into FFnet. If you really want you can go through the story using your browser's find function (CTRL+F), and replace each intsance with the horizontal line. If you really want to. I'm leaving mine with bolded, centered X's at this point for this option. Fairly hassle free. I also go into my original FFnet document and copy and paste whatever author's notes I have for the chapter/story directly into the document editor.
(Note: One of the useful features I've found with Word 2007 is when I'm using the "Replace" function, it will let me format the text that's going to be replaced. I'm nowhere near a computer with Office 2003 so I can't check to see if that feature is there. But if you want special formatting on the replacement text, that's another way to save time)
When you're done formatting everything and it looks good to your eye, you can use the "Replace Content" feature by going to the "Stories" link on the sidebar, bringing you to the "Story Edit" menu, up top it will have several links, one of which says "Content/Chapters", click there, it'll bring up another page. Scroll down to near the bottom, where it says "Replace Chapter". Pick the chapter you're replacing (only one if you've got a single chapter story), and choose the name of the document you've just saved, then click the "replace" button. This will replace the content of the chapter (eventually, since FFnet takes its time), it will not send a notice to anyone who has you on Author Alert, so all of this can be done under the radar.
If you've got it posted on LJ or your website, you've got another option. What I did was the following:
At this point I would paste it into a text editing program like Notepad. You've probably got your own version of scene markers still. Use the "Replace" function to find them like before, and replace them with what you wish. If you want, you can replace it with the <hr> tag, which is the horizontal line that FFnet uses. If you don't like this, and for example, want something like the bolded X's, do something like this.
<center>* * * * *</center>
<center><b>X X X X X</b></center>
When you've finished replacing things, copy the contents of the entire text document.
Now, go into the weirdly named FFnet Doc, and into the "Edit/Preview" menu. There should be a little button on the formatting options that says "HTML" in a little box. Click on that, and it should bring up a pop-up menu with a huge glob of text. Once again visually search for the beginning of the story (if you have author's notes or something at the beginning), and highlight the story portion. Paste the new HTML formatted story. Click the "Update" button at the bottom. It should appear as it does on your LJ, just with those "offensive" scene markers changed out. This works out easy for something with a ridiculous amount of scene breaks, such as "Revenge of the Discs".
Click the "Save/Preview" button, replace your chapter as described in the Word Doc step, and rejoice in the fact that you've beaten the Formatting Nazis.
If you have a website, it's just as easy (depending on the complexity of the coding on your story pages). You don't even need the HTML document on your computer. Navigate to where your story is on the web. Up on your browser's menu bar click "View", then "Page Source". Voila! The HTML code for your page should pop up in a text editor. Select the story portion of the HTML, and follow the same technique for LJ entries.
It's not an ideal way, as it still takes some extra work, but at least this way you aren't hunting and pecking out thousands of scene breaks. I've found it's just easiest to do everything in Word and save the stories in a seperate "FFnet Formatting" folder. However, the HTML method works just as well too if for some reason you don't have a backup document of your story.
Clear as mud?