Taken from here for prosperity.
Put this in %USERDIR%/Documents/WindowsPowerShell/profile.ps1, run a PowerShell terminal and you should see the messages "Visual Studio 2015..." pop up.
| # Set environment variables for Visual Studio Command Prompt | |
| pushd 'c:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\Tools' | |
| cmd /c "vsvars32.bat&set" | | |
| foreach { | |
| if ($_ -match "=") { | |
| $v = $_.split("="); set-item -force -path "ENV:\$($v[0])" -value "$($v[1])" | |
| } | |
| } | |
| popd | |
| write-host "`nVisual Studio 2015 Command Prompt variables set." -ForegroundColor Yellow |