Ok so i have an ibanez sz520qm and i want to install some locking tuners on it. So how do i go about it? which ones do i buy? Sperzal or Grovers? and will they fit on my guitar?
At the very least, you may have to drill some new holes for the screws that go into the back of the headstock. Worst case scenario, they don't fit at all and require major modification. I'd recommend calling a reputable repair shop and ask them what will work.
Some tuners have an outboard set-screw.. some have a pin that seat into the neck. either way you might have to drill.

I like Planet Waves tuners. They are not too expensive, solid and they have an 18:1 ratio. They also have a neat feature where they clip the excess string automatically. Grovers are nice, but Sperzels ratio is pretty low (harder to fine tune).