To set the boot delay for all your vm's to 5.000 miliseconds with PowerCLI you can use:
$spec = New-Object VMware.Vim.VirtualMachineConfigSpec
$spec.bootOptions = New-Object VMware.Vim.VirtualMachineBootOptions
$spec.bootOptions.bootDelay = 5000
Get-VM | ForEach-Object {
$_.ExtensionData.ReconfigVM_Task($spec)
}