Connect to TFS via Powershell with different user credentials - powershell

Question

I've written a Powershell script which connects to our TFS server, creates a workspace, downloads the latest source and performs a nightly build and release.
The issue I have is that it always connects with my own credentials, and from what I've read this is because I'm logged onto the machine as me. I've had a new domain user account created and we've given this admin permissions within TFS, however I'm having trouble making the script use these credentials.
Here's the part of the script which deals with the initial connection and workspace creation as it currently stands:
$subfolder = [System.Guid]::NewGuid().ToString()
$tfsServer = "http://tfsserver:8080/tfs/xyz"
$tfsCollection = [Microsoft.TeamFoundation.Client.TfsTeamProjectCollectionFactory]::GetTeamProjectCollection($tfsServer)
$tfsVersionCtrlType = [Microsoft.TeamFoundation.VersionControl.Client.VersionControlServer]
$tfsVersionCtrl = $tfsCollection.GetService([type] $tfsVersionCtrlType)
$tfsWorkspace = $tfsVersionCtrl.CreateWorkspace($subfolder, $tfsVersionCtrl.AuthenticatedUser)
For completeness, here's the rest of the "Get" logic:
$tfsWorkspace.Map($serverLocation, $localLocation)
$recursion = [Microsoft.TeamFoundation.VersionControl.Client.RecursionType]::Full
$versionSpec = [Microsoft.TeamFoundation.VersionControl.Client.VersionSpec]::Latest
$itemSpec = New-Object Microsoft.TeamFoundation.VersionControl.Client.ItemSpec($serverLocation, $recursion)
$fileRequest = New-Object Microsoft.TeamFoundation.VersionControl.Client.GetRequest($itemSpec, $versionSpec)
$getStatus = $tfsWorkspace.Get($fileRequest, [Microsoft.TeamFoundation.VersionControl.Client.GetOptions]::Overwrite)
The main problem I have when working with TFS via Powershell is the fact Microsoft keep changing their implementation, in some cases quite radically, and what we're left with is scraps of code posts and documentation littered around the internet (including here on SO) which refer to old addins and other now obsolete references which take you down a myriad of wrong paths.
Anyway, so I've had a play around with trying to create Windows credentials, PSCredentials, and the like (which don't seem to be accepted by anything), the old methods to supply an ICredential are now obsolete and I'm really not sure where to turn.
Basically, I just want to create a workspace, check out items, update files and check them back in - all as our new "tfsService" user account. Please help...
UPDATE:
Based on the answer from #Nick, I needed to make the following changes. Note the use of [System.Uri] which was required to get this working for me (not sure if that's a quirk of my setup as others didn't seem to require this). Also, I needed to put the constructor call for TfsTeamProjectCollection all on one line, as splitting it onto separate lines, as per Nick's example, wouldn't work for me either.
$cred = New-Object System.Net.NetworkCredential("username", "password", "domain")
$tfsCollection = New-Object Microsoft.TeamFoundation.Client.TfsTeamProjectCollection([System.Uri]$tfsServer, $cred)
#$tfsCollection = [Microsoft.TeamFoundation.Client.TfsTeamProjectCollectionFactory]::GetTeamProjectCollection($tfsServer)
$tfsVersionCtrlType = [Microsoft.TeamFoundation.VersionControl.Client.VersionControlServer]
$tfsVersionCtrl = $tfsCollection.GetService([type] $tfsVersionCtrlType)
$tfsWorkspace = $tfsVersionCtrl.CreateWorkspace($subfolder, $tfsVersionCtrl.AuthenticatedUser)

Answer 1

I cannot test this effectively but this seems to be a common answer on SO for this issue.
$cred = New-Object NetworkCredential("myuser", "myPassword", "mydomain")
$tfsCollection = New-Object Microsoft.TeamFoundation.Client.TfsTeamProjectCollection
(
$tfsServer,
$cred
)