Run code block locally as a different user in powershell script

Question

This is something incredibly simple, but I just can't get anything to work. I want to run a block code in a powershell script under a specific user. The keyword is locally and I'm using powershell 2.0.

Invoke-Command seems to require a remote host? I run the following and the error message that I see seems to suggest as much:

$strScriptUser = "DOMAIN\USER"
$strPass = "PASSWERD"
$PSS = ConvertTo-SecureString $strPass -AsPlainText -Force
$cred = new-object system.management.automation.PSCredential $strScriptUser,$PSS
Invoke-Command -ComputerName "." -scriptblock {
write-output "HI!"
} -Credential $cred

Start-Job with -ScriptBlock isn't supported with powershell 2.0? I run the following and the error message that I see seems to suggest as much:

$strScriptUser = "DOMAIN\USER"
$strPass = "PASSWERD"
$PSS = ConvertTo-SecureString $strPass -AsPlainText -Force
$cred = new-object system.management.automation.PSCredential $strScriptUser,$PSS
Start-Job -ScriptBlock {
write-output "HI!"
} -Credential $cred

Am I doing something wrong, or is there an alternative way?

Added: Here is what I'm trying to do in the first place. I'm making a scheduled task that runs when a user logs into/unlocks a terminal that writes logon information to a file. The scheduled task runs as the local user in order to get at the username, profile, etc. information. The logon information is then written to a log file using a different user account, which is the only account that can modify the file. To deter access to the logon credentials in the script I convert the script to an EXE using PS2EXE.

Answer 1

Here is another way.

# Get the other user's credentials
$credential = Get-Credential

# Execute a scriptblock as another user
$commands = @'
    $env:username
    # ... more commands ...
'@
Start-Process -FilePath Powershell -LoadUserProfile -Credential $credential -ArgumentList '-Command', $commands

# Execute a file as another user 
$script = '.\path\name.ps1'
Start-Process -FilePath Powershell -LoadUserProfile -Credential $credential -ArgumentList '-File', $script

With the -LoadUserProfile switch, this has the added benefit of creating the user's profile if it does not already exist.