If you have access to a vCenter Server 7.0 environment, you can use vSphere Lifecycle Manager to create and export a custom ISO.
Import the ESXi patch and vendor add-on (if applicable) zip files to the vSphere Lifecycle Manager depot. See Import Updates to the vSphere Lifecycle Manager Depot.
- Log in to vCenter Server using the vSphere Client.
- Create a new temporary cluster, selecting the Manage all hosts in the cluster with a single image check box.
- Select the ESXi version and vendor add-on (optional) and click OK.
- Export the vSphere Lifecycle Manager image as an ISO.
See Export an Image.
- Delete the temporary cluster.