How to compose a line in sources.list

[Kent West <westk@acu.edu>]

I'm wanting to try out KDE3 from

ftp://ibiblio.org/pub/packages/desktops/kde/stable/3.0.4/Debian/sid/

but I can't for the life of me figure out how to compose the appropriate 
line in /etc/apt/sources.list. I've tried several variations: with a 
trailing slash, without; with a space and trailing slash; with a ./; 
dropping the "sid/" part, separating everything after "stable" from that 
before; etc. I tried "man sources.list" and googling for info, but I 
just can't get it figure out. My current line looks like:

deb ftp://ibiblio.org/pub/packages/desktops/kde/stable/3.0.4/Debian/sid/


Can anyone help me get this working?

Thanks!

Kent