I'm afraid with the way the site is designed, you're not going to have much
luck.  It is set up so that you, the reader, have to click a drop-down list to
choose the chapter to read.

On the first page, say,
<http://www.fanfiction.net/anime/Sailor_Moon/3/0/0/1/0/0/0/0/0/1/> there are
(HREF) links to the 1st and last chapters of each entry.  But once you open
eitherof those links, the chapters are only accessible by javascript.  Looking
at the HTML source, you can see an "Input Button" tag which calls a js routine
to load the selected chapter.  So, as we all know, HTT does not push buttons
or make menu selections on a web site.  It relies strictly on links in the
source.  This site as it is, does not provide them beyond the first and most
recent chapters.

I do have some good news, though.  Assuming that all you want is the content
and the format is irrelevant, try mirroring this:
<http://m.fanfiction.net/anime/Sailor_Moon/>

You will probably want to change your scan filters to this:
-*
+m.fanfiction.net/anime/Sailor_Moon/*
+m.fanfiction.net/s/*

The mobile site does not rely on javascript so HTT can mirror it as you want.

HTH,
B^D