I found a really great article about using the TFS Client dll’s here.  However, that only worked for VS2013.  I had to fix it for VS2015.

For some interesting reason, they are no longer GACing the assemblies, nor are they in a default location.  Now they are sym-linked to the existing version.

Here is my example PowerShell code:

$vs2015Path = “C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE\CommonExtensions\Microsoft\TeamFoundation\Team Explorer”
Add-Type -Path “$vs2015Path\Microsoft.TeamFoundation.Client.dll”
Add-Type -Path “$vs2015Path\Microsoft.TeamFoundation.Common.dll”
Add-Type -Path “$vs2015Path\Microsoft.TeamFoundation.Build.Client.dll” 
Add-Type -Path “$vs2015Path\Microsoft.TeamFoundation.Build.Common.dll”
Add-Type -Path “$vs2015Path\Microsoft.TeamFoundation.WorkItemTracking.Client.dll”
Add-Type -Path “$vs2015Path\Microsoft.TeamFoundation.VersionControl.Client.dll”
Add-Type -Path “$vs2015Path\Microsoft.TeamFoundation.ProjectManagement.dll”