The k6-2 cpu is the the end of the road for the k6-2 cpu family.. Its pretty much maxed out at 500mhz. With decent cooling you could get it up to 550mhz, and if your lucky you could even get 600mhz(with VERY good cooling).
Computers have what is call a FSB(front side bus). Basically that is the speed in which the cpu interacts with the rest of you PC's subsystems. The k6-2 500 cpu runs on a 100mhz FSB. But this is only haf the story. The speed is also determined by the clock Multiplier. So in the case of the k6-2 500 it would 5(5x100=500mhz).
In order to overclock a cpu you need to either increase the FSB(100mhz) or the clock mutilplyer(x5). Like I said before teh k6-2 500 cpu is one of the last in the k6-2 line of CPU's. The faster the chip runs the more heat it produces, and the better cooling you'll need.
It also depends on the mother board the chip is plugged into. Some socket 7(the type of socket the k6-2 chip fits into) mother boards dont have FSB settings over 100.
I would look at some other sites for much more in depth informations like
www.tomshardware.com
www.overclockers.com
here at
www.anandtech.com
They each contain guides on overclocking. although most deal with more modern cpus(pIII, athlons..etc) the basics are the same.
I assume youwere hoping that you could get to say 700+, but like i said before the 500mhz k6-2 is the end of the k6-2 line. The newer chips produced are much smaller, hence less heat. The Duron for example is produced using the .18 micron fab(.25 for the k6-2). The duron Athlon and P3 are also redesigned to allow much faster mhz speeds.. longer trace lengths, and pipelines.. etc
good luck..