Have a look at this link. http://www.overclock.net/intel-cpus/300149-3ghz-q6600-oc-p5n-e-sli-6.html#post3489821
This guide refers to the Asus P5ne motherboard, but has the nuts and bolts of what's needed to overclock the chip.
I saw this guide and with first attempt had my Q6600 GO running at 3.0ghz within a few mins. It's been stable at 1.3v (my vid) no voltage increase, ever since.
There could be many reasons why your attempts haven't worked. PSU, Memory, motherboard etc etc.
You need a good quality PSU, with headroom for your overclock, as with the overclock, your power requirements increase.
On my board, the memory was an issue. The board didn't like to different size dimms in the memory slots (your 2gb + 1gb). It was ironed out after a purchase of a kit with matched 2 x 2gb dimms.
Keep trying, hopefully you'll have better luck.