Automatically creating My Site personal site

A user's My Site personal site is automatically created the first time they click on the My Content link. However, for other reasons, I need to have these personal sites already created before they log in. As a result I went looking for a script to do this.

Here is essentially what I tried:

$URL = "http://someurl"     
$accountName = "myuser"

$site = New-Object Microsoft.SharePoint.SPSite($URL) 
$context = [Microsoft.Office.Server.ServerContext]::GetContext($site) 
$upm = New-Object Microsoft.Office.Server.UserProfiles.UserProfileManager($context) 

$userprofile = $upm.GetUserProfile($accountName)
$userprofile.CreatePersonalSite();

This was not successful in creating the personal site.

The account under which I run this has administrator rights on the User Profile Service Application, and is in the Farm Administrators Group. In the ULS there was an entry for "Access Denied". I also do have Self Service Site Creation enabled.

Seeing as this was an "Access Denied" I then tried to run the script as the SharePoint Farm Account. This was successful. Unfortunately, I do not want to run this script as the Farm Account.

Next step was to try running this with elevated privileges which involved putting my code within this:

[Microsoft.SharePoint.SPSecurity]::RunWithElevatedPrivileges()

Still no luck

Next was to try using a different user token like this:

$site = New-Object Microsoft.SharePoint.SPSite("myurl", [Microsoft.SharePoint.SPUserToken]::SystemAccount)

or even with the user account for which I am creating the personal site.

Still no luck.

At this point, I gave up and put my script into the Task Scheduler to be executed as the Farm Account.

It would be nice to know exactly what permission is missing.