# Get each user profile SID and Path to the profile
$UserProfiles = Get-ItemProperty "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList\*" | Where {$_.PSChildName -match "S-1-5-21-(\d+-?){4}$" } | Select-Object @{Name="SID"; Expression={$_.PSChildName}}, @{Name="UserHive";Expression={"$($_.ProfileImagePath)\NTuser.dat"}}

# Add in the .DEFAULT User Profile
$DefaultProfile = "" | Select-Object SID, UserHive
$DefaultProfile.SID = ".DEFAULT"
$DefaultProfile.Userhive = "C:\Users\Public\NTuser.dat"
$UserProfiles += $DefaultProfile

# Loop through each profile on the machine
Foreach ($UserProfile in $UserProfiles) {
    # Load User ntuser.dat if it's not already loaded
    If (($ProfileWasLoaded = Test-Path Registry::HKEY_USERS\$($UserProfile.SID)) -eq $false) {
        Start-Process -FilePath "CMD.EXE" -ArgumentList "/C REG.EXE LOAD HKU\$($UserProfile.SID) $($UserProfile.UserHive)" -Wait -WindowStyle Hidden
    }

# Manipulate the registry

$key = "Registry::HKEY_USERS\$($UserProfile.SID)\Software\Microsoft\Office\15.0\Identity"
New-Item -Path $key -Force | Out-Null
New-ItemProperty -Path $key -Name "EnableADAL" -Value 0x00000001 -PropertyType DWORD -Force | Out-Null
New-ItemProperty -Path $key -Name "Version" -Value 0x00000001 -PropertyType DWORD -Force | Out-Null

# Unload NTuser.dat
If ($ProfileWasLoaded -eq $false) {
    [gc]::Collect()
    Start-Sleep 1
    Start-Process -FilePath "CMD.EXE" -ArgumentList "/C REG.EXE UNLOAD HKU\$($UserProfile.SID)" -Wait -WindowStyle Hidden| Out-Null
}