Where/How to get access to the old Debian repositories ?

[Gilles van Ruymbeke <ruymbeke@rocketmail.com>]

Hello,
Where/How to get access to the old Debian repositories ?
I need to add/upgrade some packages on a customized version of Knoppix 5.1.1.
I only have the option to upgrade to some of the latest packages
which more or less will force to upgrade almost everything on the system
1000+ packages including the kernel which is obviously not desirable.
I am only looking to add a couple missing packages being compatible
with my existing running system and avoid remastering
the new Knoppix release which will be a hughe work.
Is there a list of the old Debian/Knoppix repositories available somewhere ?
Thanks for your help,
Gilles