Please see this thread on a fckeditor plugin:
http://forums.b2evolution.net/viewtopic.php?t=6848

I installed and removed it because it does not work well with other plugins, and the filebrowser cannot be integrated.

Perhaps trying to hack one of the existing editors into b2evo is a wrong direction? Perhaps developing a "native" and light-weight WYSIWYG editor from scratch is easier? That way at least we can ensure all the other cool plugins like Youtube and CC can be compatible with it.

Just some thoughts.

You could always try ones that are not built into the blog if you are that desperate;
http://forums.b2evolution.net/viewtopic.php?t=9664&start=0&postdays=0&postorder=asc&highlight=

CRT, Writing our own wysiwyg editor would take forever. There are lots of good solutions out there, but not without a price. (Personally i like wysiwyg pro). But thanks for pointing out the fckeditor plugin to suburbia.