You could pick up a Y-connector cable. What this cable would do is allow two fans to connect to one connector, much like a telephone line splitter would allow a two phone bases to connecto to one wall jack.
Thank you for posting a link to your board. I understand your problem. Three-pin and 4-pin of that type are interchangeable.
The 4th pin on these new CPU coolers is for a new type of fan speed control. You can use it on a 3-pin connector just fine.
Only two pins are power (12v and ground), the third is RPM detection. The forth is for Pulse Width Modulation. So the third pin is not required for the fan to operate, and the forth pin is only required for PWM.