Would not suggest overclocking a pentium d. They ran hot in the first place, so you need exceptional cooling. Not going to gain a lot anyway, these were some of the worst processors Intel ever released. But if you are determined, a google search will turn up about a thousand results that will tell how to do it, its an old processor and its been done to death over and over and over.
BTW ,, i have try OC to 3306mhz. And the temp is 61c at full load, 45c at idle. And when i try to OC to up 3600mhz , my pc cant boot.