You can do this - I have done it. There's a +12v lead, a ground lead, a PWM lead, and a tach lead, just like on a PWM fan. The ends, pins and crimpers are readily available on Amazon and are a good thing to have for other custom cabling projects.
There's a catch though - once you do this, you have to be careful what you plug your pump into. The pump pulls about 0.7a, which is -way- more than most fans and may be too much for the headers on some cheaper motherboards. Make sure you've got 1A headers available to you before making this mod.