It is a configuration set by the Opera Mini servers and you have no option to configure it by yourself. Why would you want it?
As a developer myself I agree with what Opera Mini is achieving with the extreme mode. However, website I am working on needs this to be done, as we noticed there are quite a few websites which have got this configuration already. It would be grateful if you could help me with the pointer who/how to be contacted for the configuration to be set for a website. So I can pass this to people above me in organizational structure to get this done.