Now that we have our scripts in place to emulate MediaWiki functionalities, copied over the images and files, and prepared html-pages for all our relevant articles, we can send the pages to SharePoint.
With this script, you prepare the articles one by one, create files for it, and call a PowerShell script which does the actual uploading (see below). Don't forget to update the rootPath to whatever you're using.
Now for the PowerShell script. Put it in a subdirectory powershell in the articles directory. Don't forget to change the siteURL, your username and your password on line 78. And of course the script directory on line 4.
You'll notice the script is calling a dll. You actually need a bunch of them. Create a subdirectory dll in your powershell folder, and put these dlls there: client.dll, microsoft.office.client.policy.dll, microsoft.office.sharepoint.tools.dll, microsoft.sharepoint.client.dll, microsoft.sharepoint.client.publishing.dll, microsoft.sharepoint.client.publishing.silverlight.dll, microsoft.sharepoint.client.runtime.dll, microsoft.sharepoint.client.silverlight.dll, microsoft.sharepoint.client.silverlight.runtime.dll, microsoft.sharepoint.client.taxonomy.dll, microsoft.sharepoint.client.taxonomy.silverlight.dll, microsoft.sharepoint.client.userprofiles.dll, microsoft.sharepoint.client.userprofiles.phone.dll, microsoft.sharepoint.client.userprofiles.silverlight.dll, microsoft.sharepoint.dll. I'm not sure if they're all needed, but hey, this bunch made it work for me. I'll upload a zip of them somewhere later, if somebody needs them and can't find them anywhere else.