Overview
The Visual Studio Developer Command Prompt is a command window that loads up a bunch of useful environmental enhancements when it starts. This let's you access things like sn.exe from your command window. However, it loads up in cmd.exe and I prefer using PowerShell 'cos it's proper useful! This article shows one way making PowerShell act like the Developer Command Prompt.
Adjust your PowerShell Profile
When PowerShell loads it looks for a profile file under your user profile and loads that if found. By default, the profile file is:
\WindowsPowerShell\Microsoft.PowerShell_profile.ps1
Note that you can access your documents folder path from PowerShell like so:
$([environment]::getfolderpath("mydocuments")
If that file isn't there, create it, add the following code and save it:
Adjust the environment in the last line above according to your VS installation.
Load in PowerShell
Open up a new PowerShell window (existing windows will not have loaded the profile we've just saved). Type sn and to show that you don't have access to sn.exe:

Then type As-VSPrompt and hit . This will load up the Developer Command Prompt profile. Type sn and again and you see sn.exe reporting for duty:
