I personally haven't but it depends on what all you're gonna do. You will need a spring compressor and there are "store bought" ones like the Venturi one @ at places like Pyramyd Air or YT videos for diy compressor builds & tunes. You will also need a kit like the Vortek if you're going all out unless you just replace the seal. While you have it down search YT videos for trigger tweaks also.
Several years ago I sent one of my RWS34T06's to Umarex to break it open and replace the spring, spring guide & seal while under wty.; they did an amazing job btw with a quick turn around. Good luck and keep us posted on your project; plus we really like pictures.