Write to a file
Use Set-Content and Add-Content
Set-Content "C:\Program Files\Sublime Text 2\subl.bat" "@echo off" Add-Content "C:\Program Files\Sublime Text 2\subl.bat" "sublime_text.exe %1"
Adding to environmental path variable
from http://softwaresalariman.blogspot.co.uk/2008/01/add-path-environment-variable-in.html
Set-Content "C:\Program Files\Sublime Text 2\subl.bat" "@echo off" Add-Content "C:\Program Files\Sublime Text 2\subl.bat" "sublime_text.exe %1" [System.Environment]::SetEnvironmentVariable("PATH", $Env:Path + ";C:\Program Files\Sublime Text 2", "Machine")