Yesterday I wanted to open the Group Policy editor (or "Group Policy Management Editor") for a specific GP object through PowerShell, but there is no "Edit-GPO" cmdlet. I quickly checked from the task manager how the GPMC opens the editor, and made my own:

function Edit-GPO([guid]$guid){
$domain = Get-ADDomain
# Operate on PDC to help consistency
$GPPath= "LDAP://{0}/CN={{{1}}},{2}" -f $server,$guid,$PoliciesPath
gpme.msc "/GPOBJECT:`"$GPPath`""

My function binds to the PDC for the same reason the GPMC does - it helps consistency. If you don't like it, you can modify the $server variable to point at something else.
For example, this is how you open the gpme for the default domain policy:

Get-GPO 'Default Domain Policy' | %{Edit-GPO $_.Id}

And this is how you open it for every GP with user settings enabled:

Get-GPO -All | ?{$_.GpoStatus -band ([Microsoft.GroupPolicy.GpoStatus]::ComputerSettingsDisabled)} | %{Edit-GPO $_.Id}