In EASA-land, if its not a procedure in the AMM or MEL, you'll need approval from your Airworthiness Authority, and they are going to even consider your request without a recommendation from the Type Certificate Holder. Obviously every type (and TCH) is different.
Again, obviously, if the Red-hordes are storming the ramparts you might decide to just do it and sort out the niceties later, but make sure you've got footage of the Red-hordes.