I've had a number of Backstops on various Ibanez guitars (Jems and an S-Series somethingorother and a Maxxas) and I never much liked them... Steve uses them on most of his guitars, so they've garnered a certain caché (that I turned in to cold hard $$$ when I sold my last two Backstops for crazy prices a while back), but I found they stiffen the trem somewhat, add a weird feeling "notch" or "center" position to the trem motion, and can be quite difficult to adjust properly (and I set up all my own guitars, including shimming the necks and setting up the Floyd Rose trems, so when I say it's a pain, I mean A-GO-NY

) I, personally, would NOT install one on another of my guitars...
Anyway, the most important thing about installing these things is to ensure that you have the proper clearance - that the trem route in the back of the guitar is deep enough that the middle spring in the trem won't rub on the Backstop when it's installed. IME, most guitars DO NOT have a deep enough trem route. If the spring touches the Backstop at all, even very, very lightly, you will NEVER get it adjusted properly, so the only option then is to get someone to deepen your trem route or give up, and work on setting up your trem without a Backstop - I would suggest the latter...
The other thing to worry about is that the thing is installed ABSOLUTELY perpendicular to the trem block, which requires a pretty precise install. You don't want the stoppers on the Backstop coming into contact with the trem block at any kind of angle at all - you want full contact of the round plugs flush against the trem block when it's all installed and set up properly...
my 2¢