Adding a system path environment variable via command line?

I'm trying to add a variable to the system path via command line but can't find the variable for "system path"

If I run the following code:

setx path "%path%;C:\Python27\;C:\Python27\Scripts\"

It adds it to the local path, not the system path so I tried things like:

setx syspath "%syspath%;C:\Python27\;C:\Python27\Scripts\"
setx systempath "%systempath%;C:\Python27\;C:\Python27\Scripts\"

I can't find anything located at http://technet.microsoft.com/en-us/library/cc755104.aspx other than the ability to edit the local path variable.

I'm not looking for a way to do it via the GUI, I'm looking ONLY for a way to do it by code (command line hopefully)

In Autoit for example I can edit it via registry:

$SystemPath = RegRead("HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment", "Path")
If StringRight($SystemPath, 1) = ";" Then
    RegWrite("HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment", "Path", "REG_SZ", $SystemPath & "C:\Python27\;C:\Python27\Scripts\")
Else
    RegWrite("HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment", "Path", "REG_SZ", $SystemPath & ";C:\Python27\;C:\Python27\Scripts\")
EndIf

or via GUI

Run("SystemPropertiesAdvanced.exe")
WinWait("System Properties")
ControlClick("System Properties", "Enviro&nment Variables...", "[CLASS:Button; INSTANCE:7]")
WinWait("Environment Variables")
ControlListView("Environment Variables", "", "[CLASS:SysListView32; INSTANCE:2]", "Select", ControlListView("Environment Variables", "", "[CLASS:SysListView32; INSTANCE:2]", "FindItem", "Path"))
ControlClick("Environment Variables", "", "[CLASS:Button; INSTANCE:7]")
WinWait("Edit System Variable")
$SystemPath = ControlGetText("Edit System Variable", "", "[CLASS:Edit; INSTANCE:2]")

If StringRight($SystemPath, 1) = ";" Then
    ControlSetText("", "", "", $SystemPath & "C:\Python27\;C:\Python27\Scripts\")
Else
    ControlSetText("", "", "", $SystemPath & ";C:\Python27\;C:\Python27\Scripts\")
EndIf

ControlClick("Edit System Variable", "", "[CLASS:Button; INSTANCE:1]")
ControlClick("Environment Variables", "", "[CLASS:Button; INSTANCE:9]")
ControlClick("System Properties", "", "[CLASS:Button; INSTANCE:8]")