Installing WordPress Multisite with different domains

I own a few domains: IIVQ.net (this has always been the host for my e-mail-domain), citrastructurae.net and it’s brother xn--citrastructur-ggb.net (see) and urbanandrural.net. I made a few posts on citrastructuræ, but wanted to keep that page for it’s subject while also writing about the tinkerings I do, mainly to serve as a memory to myself …