You can ftp Sparkle from sumex-aim.stanford.edu (or a mirror like 
mrcnext.cso.uiuc.edu) in info-mac/grf/util.

I no longer support systems earlier than System 7.5. If you want to ftp 
all the pieces of Sparkle separately, I don't have time to help you find 
them. I'd recommend you start your search at 
ftp.support.apple.com in Apple SW Updates/US/Macintosh/System Software 
but beyond that, I can't help.

I'd recommend you install System 7.5. A full 7.5 install will install everything Sparkle 
needs.