I cannot say anything about the editor and opera because I never used opera, but if you want to use this editor on your DNN, you only have to install this provider.

There is a new release almost ready, but while it comes, you can download the previous version (Using FCKEditor 2.2) from http://dnn.tiendaboliviana.com

After the first DNN release of the FCKEditor provider, file downloads will be moved to the project page on this site.

ok. following the page you sent. You must modify the file:

Providers\HtmlEditorProviders\DSFCKEditorProvider\Custom\fckconfig.js

by adding the following line:

oFCKeditor.EnableOpera = true ;

after the basepath line(oFCKeditor.BasePath    =...)

I don't use opera, so I don't know if it really works. Please post your results here for everyone to know.

REMEMBER: Clear your browser cache after modifying that file.