Completely disassemble?
Not quite.
Your guitar will go out of tune, and you need to have some allen wrenches handy to replace a string.
You unlock the nut, and you unlock the "pad" in the bridge itself, snip off the ball end of the new string, insert it into the bridge, tighten the "pad", feed the string through the nut (unless you remove the locking pad completely), feed the string into the tuner, snip of the excess, wind it up, stretch the string (repeatedly, for tuning stability), tune, lock the nut, and you're good to go.
Back in the day, when I was really up to speed, I could change a complete set of strings, and intonate the sucker in about 15-20 minutes.
With a good quality "Floyd" (one that stays in tune, no low-end cheap crap!) the only drawback is that you go out of tune when you break a string.
ok cool beans thanks