I burned a DVD-R of Arch Linux and tried to install it, but the May image (what I was using) did not include the wifi libraries, so I couldn't connect to the repo to install. I burned a DVD-R of the April image, but I still can't get the thing to work, even though now I can use wifi-menu in netctl. I have a Linux Mint liveCD from which Linux Mint can be installed, but can I just connect to repos with that liveCD and then just install Arch from the nice sheltered environment of the liveCD?
It does include wifi libraries only it does have no wifi tools. I managed to install it from this archlinux version dvd using wi-fi interface in manual mode: https://wiki.archlinux.org/index.php/Wireless_Setup#Manual_setup and https://wiki.archlinux.org/index.php/WPA_Supplicant.
The problem is that you need pacman package manager not apt-get (the one mint have). It should be theoretically possible to build archlinux from scratch in chroot from other distro, however it is not only undocumented, also it equates creating your own distro. Your best shot probably is to get network working properly, or make basic instalation on other PC and clone partition. Also do not forget to install in your new instalation wpa_supplicant and copy your network configuration from an instalation environment.