I ended up placing the payload files on a shared directory and copied them over. It works OK doing it this way.
$payloadFilename = "hyperic-hqee-installer-4.6.0.1.msi"
$guestInstallPath = "C:\Hyperic"
$scriptCreateDir = "New-Item -type directory -Path"+$guestInstallPath
$payloadPath = "\\[IP Address]\hyperic\Server\$payloadFilename"
...
Invoke-VMScript -VM $VM -ScriptText "Copy-Item $payloadPath -Destination $guestInstallPath" -GuestCredential $cred