ここ見たほうがいいと思うよ
http://wiki.archlinux.org/index.php/Official_Arch_Linux_Install_Guide
http://wiki.archlinux.org/index.php/Beginners_Guide

そこのコピペだけど、installCD起動してコマンドプロンプト出て正常
Login and Loading a non-US Keymap
If you need to load a non-US keymap and/or want to set a different console font, use the "km" utility.
km　　※これでキーマップ変える
Running Setup
Now you can run /arch/setup to invoke the installer program.
/arch/setup　※これでinstallが始まる