First you will probably find things easier with the TFS PowerShell snapin from the TFS PowerToys (it isn't included in the default install, you need to select from a custom install).
Then load into a 32bit instance of PowerShell with:
Add-PSSnapin 'Microsoft.TeamFoundation.PowerShell'
Use:
gcm -noun tfs*
to see a list of cmdlets it provides.
You can use Get-TFsItemProperty to examine individual source control items and Update-TfsWorkspace to add them to your wokspace (and thus get locally).
Richard J Cox