Updating parameters using SPE

Question

I'm running a script in which I want to mark as checked all renderings of a specific template with the Vary By Data parameter. But running the script it is adding to the Additional Parameters the value as opposed to checking the checkbox for the respective parameter as shown bellow:

Anyone know what I'm missing? Here is my script

$items = Get-ChildItem -Recurse | Where-Object {$_.TemplateID -match "{79A0F7AB-17C8-422C-B927-82A1EC666ABC}"} | ForEach-Object {
$renderingInstance = Get-Rendering -Item $_ -Rendering $rendering
if($renderingInstance){
    Set-Rendering -Item $_ -Instance $renderingInstance -Parameter @{
        VaryByData = "$true"
    }
}}

Answer 1

It's actually easier than that (only showing partial code):

if ($renderingInstance) {
    $renderingInstance.Cachable = 1
    $renderingInstance.VaryByData = 1
    Set-Rendering -Item $_ -Instance $renderingInstance
}

This will update the checkboxes on the shared layout. You can omit the Cachable (sic) setting if your rendering instances are already set to be cached, or if don't want to activate caching for all of them.