First of all, Leech uses Curl to do the actual downloading of the file, so you might want to make sure you've got Curl before you try using Leech. Curl is available at http://curl.haxx.se/
This is version 0.4.5, which I still consider a development release. Version 0.4.0 was an (almost) complete rewrite and the development stage is getting closer to beta; it works, but there are still bugs. Let me know if you find any, or, even better, feel free to fix them and mail them to me ;)
By default, access to Leech is unrestricted. This can be changed by setting the global variable $USE_AUTH to True. After that, Leech should be asking for a username and a password. There's a sample leech.pw which is best installed in a directory that's at least readable by Apache. I recommend creating an etc directory in Apache's directory, /usr/local/apache/etc for example.
You can use Apache's htpasswd tool to manage the password file. The example password file contains a user leech_user with password leech_pass, so you should at least change the password.
Another thing; Leech is written in PHP, so you'll need a web __server__ to use Leech. I hope everybody who downloads Leech realises this :-)
In the Personal Toolbar Folder (or equivalent), add a bookmark similar to the following:
This should open a new window with a Leech Form, with the URL field filled in. Nifty! :-)
Please direct any bug reports, questions, comments or suggestions to me, Kars Meyboom (firstname.lastname@example.org).