The first step is to register the remote wiki with an InterWiki name. This can either be done on the page InterWikiMap or in the file intermap.txt (see HelpOnConfiguration).
In your wikiconfig.py set interwikiname. It is commented out by default.
Then it is necessary to create a kind of "job page" that contains all parameters for the synchronisation. This page will be extended by the log of the sync process as well. See below for allowed parameters. The parameters have to be written in the dictionary format (see HelpOnDictionaries). It is generally a nice example and helpful to use the page SyncJobTemplate that already has some parameters in it.
After that, you can simply select SyncPages from the dropdown menu and start the synchronisation.