Two questions for you:
1.) How? The Darkstone has a set neck. If you want to replace the body you will only be left with a pile of chrome-plated hardware. Unless you get out the hacksaw?
2.) Why?? The Darkstone is hands down the finest Ibanez ever created. It is beautiful to hold, and I like that it has features (like the fretboard binding) that are practically invisible to the audience, but make the guitar look extra sweet to the player. And it sounds phenomenal. It will still be sustaining notes even after you have chopped the neck off!
Tell you what - send me your Darkstone and I'll send you back one of my RG's. Plenty of replacement bodies available for those...