For servers without CD drive or remote KVM you might want to use an USB Flash Drive to install ESXi to the hardware. This post explains how to create a bootable ESXi Installer USB Flash Drive in less than 2 minutes. The Flash Drive will work totally identical to an Installable CD.

Additional Hint

When you boot a server with this USB Flash Drive the ESXi Installer will copy the whole installer to the memory which means that you can install ESXi to the device where you are installing from. Just select it during the installation. This also works for diskless ESXi hosts where you want to install ESXi to an SD Card.