I haven't done it on a Jem, but I did on an RG560. It works okay but it's not as stable as the
locking nut was. I think the best way for
locking tuners to work is with a guitar that has a well-cut and dressed standard nut. But the strings have quite an area in the path of the locking nut area to travel over, so for me personally, I fear that more area to bind on and throw tuning out. With the RG, I stretched the hell out of the strings, and yes, it was reasonably in tune most of the time. Certainly within the fine-tuners' corrections. But I found the locking nut itself to be the better tuning stability.
Perhaps you could mount one of those wrench holders on the headstock...always keep a wrench there for that emergenct you fear. Either way...if it's a gig situation, you're gonna eat time unlocking, changing the string, stretching, tuning, stretching, tuning...etc. So the best bet? Get another Jem!!!! lol... Two per tuning...
