How to create a specific scale zoom level?

[Algorithman]

First: great project, didn't know OSM/OTM are that good now.

To my question: I'm in particularly in need of 1:100000 and 1:200000. Can you point me in the direction where to look/what to change to set custom zoom levels?

Thx in advance

PS: Needed for printing, not so much for web application.