Multi-Step Infusion Mash. Dunkel, need advice.

I want to make sure im doing things correctly. Im brewing up a dunkel.

http://www.northernbrewer.com/documentation/allgrain/AG-Dunkelweizen.pdf

Id like to do the multi-step mashing process if possible. My MLT is a converted 52qt Coleman Xtreme cooler.

So there are 4 temps i need to hit, and i have to do it without a burner and without going over my MLT capacity.

Im trying to figure out how much water to add at what temp to hit my targets. Im not sure how to factor in the water volume for each additional step.

so 10.25lbs of grain at 70F and 1qt/lb is 10.25qts of 134F water to get to 122F

so next its still 10.25lbs of grain + water and i need to get to 149F

Trying to brew on Saturday. Any help you give would be great. I could do a single step infusion but i feel like that the multi step will taste better.
but

This may not be the answer you are looking for, but I will tell you what I do with a multi-step mash with a similar Cooler-MLT set-up: I do all my mash steps in the boiling kettle, and then I lauter and sparge in the MLT. This makes it simple, accurate, and fast.

Scooby_Brew said:

This may not be the answer you are looking for, but I will tell you what I do with a multi-step mash with a similar Cooler-MLT set-up: I do all my mash steps in the boiling kettle, and then I lauter and sparge in the MLT. This makes it simple, accurate, and fast.

Click to expand...

so basically your saying to use the the MLT like a strainer. So put grains and water in the boil kettle, use that to hit my mash points, then pour it all in the mlt. Drain and sparge as usual. How long do you normally let it all settle before draining back into the boil kettle?

Alternately, you could do a decoction with that equipment.

I did a four step infusion mash a few weeks ago in my 40 qt cooler. The infusion calculator over at tastybrew was very helpful. Basically I mashed in at 120 with 1 qt per lb, then used the calculator to adjust my strike temps such that my fourth infusion brought me up to 2 qt per lb. Worked as planned.

From 120, I went to 135, then 145, then 150, each for a half hour. Had about 13 lb of grain for a Belgian golden strong.