On the front page of snapshot.debian.org are Usage instructions. Follow your link all the way until you see the timestamp string in the path:
Code:
http://snapshot.debian.org/archive/debian/20060728T000000Z/pool/main/a/apt/apt_0.6.45_sparc.deb
and then it says to arrange sources.list like this (if 3.0 is Woody)
1)
Code:
deb http://snapshot.debian.org/archive/debian/20060728T000000Z\ woody main
deb-src http://snapshot.debian.org/archive/debian/20060728T000000Z/ woody main
deb http://snapshot.debian.org/archive/debian-security/20060728T000000Z/ woody/updates main
deb-src http://snapshot.debian.org/archive/debian-security/20060728T000000Z/ woody/updates main
2) apt-get install apt=0.6.45
3) sources.list is loaded in order from top
4) Of course, there is always something we need to know before we know it! :-)
I'd definitely use the -s install option first to see what might happen. Good luck!