Typically the two cooler method would involve fly (continuous) sparging. But you can do batch sparging.
http://hbd.org/cascade/dennybrew
http://www.howtobrew.com/section3/chapter16.html
Batch sparging you recirculate the wort to get grain particles filtered out by create a filter bed with the grain husks. Then completely drain the cooler. Add more water, recirculate and drain.
Fly sparging you recirculate the wort, then start to drain the cooler while at the same time adding fresh water to to cooler. Trying to maintain about 1" of water above the grain bed.
With either method, keep an extra .5-1g of hot water available just in case you calculation are off. Grain absorption rate can vary by how fine of a crush the grain is. And each set up has it’s own “dead space” to account for. .1 to .15qts/lb is a good place to start for the water loss.
To help with your water calclulation you can use Mashwater 3.3 that JT built.
http://gnipsel.com/beer/software/beer-software.html
Qbrew is also a free recipe program you can use to keep track of your brews. And give you an idea what would happen if you added another pound of grain to a recipe if your gravity comes out a bit low.