With my server in place, I ran a memtest on it … which with 128G took a while ;)
And then installed Proxmox 4, using a bootable USB that I’d created on my Mac from the ISO downloaded from Proxmox’s website. To create the bootable USB, create the img file:
hdiutil convert -format UDRW -o target.img source.iso and then burn it to USB:
sudo dd if=target.img of=/dev/rdiskN bs=1m Replace N with the correct device based on diskutil list output.