Please forgive me my wise ass sense of humor, I could not really answer a question like "How do I integrate mojoPortal with x?", it all depends on x and I have no idea about all the possible values of x and what it would take to integrate with it so I chose to have fun with the question, no offense or unkindness intended. I'll try to make up for it with a more sensible answer.
In my understanding of what a wiki is, it seems to be made up of 3 main ingredients.
1. an option to allow anyone to edit. You can do this in mojoportal today at least for anyone whohas a login if you enable editing by authenticated users role which includes everyone with an account. I would not care to do this myself, that is allow anyone who registers on the site to edit. I prefer to put trusted people in roles that can edit and not just trust everyone by default.
2. keeping of history of every change and version of content so you can always revert. This is a planned feature in the near term for mojoportal.
3. a wiki markup language. Yuck, something only a developer could love. I'll just use FCKeditor, I don't want to learn some wiki markup stuff, I already know html if I need it and most things I'd rather use the wysiwyg
So really the keeping of history is the only thing mojoportal lacks that is of value in my opinion and this is coming soon. If that will meet your needs perhaps no integration with a wiki system is needed.