You're limited to whatever overclock will output 130W or less.
That sucks balls.
@ OP, it would be helpful if you could post some pics of your BIOS, it would make it easier for us to explain.
But you need to know the basics first. The CPU frequency is determined by the multiplier and bus speed (I can't call it the FSB, because it's not anymore), which I believe is 133x20. Since the 920 has a locked multiplier, you'd need to increase the bus speed (133) to overclock.
I don't actually own one of these things so I can't help you with much else ATM, although I'm pretty sure it's identical to Phenom in terms of memory etc. Posting some pics of your BIOS would help a lot.