it's the same as overclocking any other boards. make sure you know how to reset the cmos, and that you are prepared to do it quickly.
put the ram at its lowest speeds and its highest timings, and keep upping the fsb until it becomes unstable and won't boot. oh and make sure you have the cpu features like eist and such disabled.
once you find the speed it wont boot at, lower it by 5-10fsb until it will run prime95 stable for a little while. just get to know your board.
from there, you can narrow down to what is making it unstable, if its your cpu then add some cpu voltage. if its your fsb, add some northbridge voltage. note: adding voltage adds a lot of heat, don't do it unless you have a high quality heatsink or some sort of after-market cooling.
edit: if you want to know how far it can be pushed, that really depends on a lot of other factors... i.e. one asus p5e might hit 2000fsb and another will only hit 1600fsb. they're never exactly the same, maybe not THAT different but you never really know until you tweak and test and keep trying new things with it. change settings around test how stable it is, and hope it doesn't crash on you.