Well, I’ve been tinkering with KVM the last few days and I’ve been stuck accessing the KVM guests (as the guests are running on a host I don’t have my Xorg server running on). After a bit of searching, I actually found what I was looking for.

Piecing together from both sources, to connect to a KVM host, that has SSH running on a different port:

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virt-viewer --connect qemu+ssh://root@kvm.home.barfoo.org:222/system guest