Postgresql 8.4 with debian 8

I have an old web-based solution which i need to reinstall to gather some data. Unfortunately it only runs with PG 8.4. So i installed PG 8.4 according to those instructions:

http://askubuntu.com/questions/309615/how-to-install-postgresql-8-4

Then i want to check for that server in webmin and it says that the server has not been started.
Interestingly enough ps -el shows me four postgres processes.

Also, the postgres 8.4 logfile tells me something of incomplete startup package

My datacenter only allows to use debian 8, or Ubuntu 14.04. I thought Debian would be the better solution but i am open to switch.

I am forced to install this software; so i really appreciate any help.

Tia

j_m