People want to do a lot of things, a lot of different things. People don't like to be forced into something, the transition between work and fun should be smooth so that people have fun while working.
This means that you have to connect advantages of being part of a Wiki with the work which has to be done. If you take a look at Wikipedia, you can see that they have pages for each user on which they can display their doings on the site itself. While you usually don't stumble upon it during a normal visit, users who contribute to the Wiki know of it and look up different profiles to validate, for example, a user's statement. There is a lot of gamification: do that, gain that, don't do that, gain that.
You should connect the work with social rewards. As you have written the answer, you look for a long-term solution. Let's shortly discuss short-term solutions which can be applied internally.
- Your boss can set up rewards for writing documentations or making edits. The more you participate, the more money you receive.
- You can connect participation with a better treatment (shorter waiting times in the cafeteria for example).
- You can put in a good word for somebody so that the one who participated is informed of the next free better-paid position first.
However, these are just short-term solutions if you have to get a bulk of information into the Wiki quickly. It won't work forever, especially because it might be seen unfair among colleagues. It can create a competition of who gets what first. Nevertheless, this isn't the goal in a Wiki-oriented project: you want to cooperate and don't hinder each other.
Possible long-term solutions are:
- Put people formally in charge for specific fields.
- Use virtual rewards.
- Make "everything" discussable.
Now, let's dive more into detail.
Putting people formally in charge of something is a social reward which is, if you think about it carefully, not a reward at all. People will feel obligated to take care of their responsibilities to not disappoint you or anyone else. By formally promoting them, they will feel even more important and are careful to not mess around. However, by "just" formally promoting someone, you and the community have still enough influence to change something.
"Hey, I want you to take care of the project while I'm not around, okay?"
"Yes, no problem, I can do that."
"Can you inform me of everything that changes and is worth of reporting?"
"Yes, will do."
You leave them a little freedom to take actions themselves but they know that they have to work with you on it. Of course, you shouldn't overuse it. It's easy to apply but can easily backfire, too.
Virtual rewards are great. It's the same like here on SE. You participate and everybody will know it because you earn badges, reputation or something else for participating. You can introduce it as something that is supposed to measure the effort put into the project by an individual. Then add a little bit democracy by creating a committee which is supposed to rate the overall quality of content. The committee is elected semiannually, annually, how the users want it to be. You can also think about giving the committee the privilege to mark a page as featured or especially elaborated.
The last point is somewhat difficult because you have to balance a lot of things at once. Not everything should discussable, just the content should be. To avoid discussions about the technical architecture or anything related to the technical part, ask everybody what they want to see in the beginning. By doing that, you can rely on the argument that the technical part is like the majority wanted it to be.
However, content should be always discussable, and you should encourage it. Imagine someone has a little trick to get something going more quickly, encourage them to add it to your "Tips & Tricks" page so everyone can use it. You can put contributions of new members on a waiting list and approve or reject it then, but there should always be a clearly visible opportunity to help. Clarity is crucial for a Wiki which is a knowledge archive, hence a kind of a formal discussion board.
In order to make users want to use your platform, it mustn't be a hassle to use. It should be easy to use, and patterns used through your Wiki should be clear. Reward contributions by adding virtual rewards. Make it desirable by pointing out that it will improve the general workflow (no more searching in dozens of documents to find the one paragraph). Nonetheless, it's desirable to do to a slow transition of the old system to the new one to learn all rules and policies properly. "Tradition" and workflow has to be learned, and that's not accomplished in a day.