What I want to do is get a specific version of a file from TFS to a location other than my workspace using the command line (either tf.exe or powershell)
rem tf.exe
tf view $/path/to/file.txt /version:1234 > %temp%\file.txt
# powershell
$tfs = get-tfsserver $hostName -all
$tfs.vcs.DownloadFile($serverPath, $fileName)
# even better: manipulate entirely in-memory
$item = $tfs.vcs.GetItem($serverPath) # tons of GetItem(s) overloads available
$contents = ( [io.streamreader]$item.DownloadFile() ).ReadToEnd()
$contents | ? { some-condition } | do-coolstuff