gpo startup script via registry

Hello everyone.

Is it even possible to add/edit a gpo startup script through registry?
Google is vague on the question. I mean it ignores the "registry" part and rumbles on to tell me, in millions of search results, how to work gpo with gpedit. 

Script is added using powershell, absolutely identical to whatever gpedit would write to the registry, but gpedit refuses to acknowledge my input, the startup script dialog stays empty. 

Do I really have to resort to using AutoIT for a task as simple as this?