I thought that's what you were talking about. Can you do it, yes. Should you do it, probably not. The P4 has a horrible IPC, so even at 4GHz it would lose to a low clocked C2D based CPU. (rev 2 of your board supports those.) You also have to bump the voltage up quite high to get to 4GHz if I remember that article correctly. This means lots of heat, and not a lot of life for the chip. Last, considering you can get an AMD quad for $100, there is no reason to do this assuming your buying new. The article is YEARS old, no one should care about this anymore.
Check to see if you have a rev 2 board. If you do, get a C2D based chip. If not, sell what you have and buy something that does.
myself and my best mate both bought 805's when they first came out the he had the 945 chipset with water cooling without that much luck over 3.4ghz but i got an nforce 4 chipset at 3.75ghz on almost stock voltages at first before board cooked its northbridge then i got a 965 chipset much better than the 945 and that was able to get 3.6ghz on the same voltage both on big air cooling. dont bother getting one though even the cheapest pentium dual cores these days will smoke em prob at stock speed not to mention they overclock just as high, just as easily as the 805.