Ben,
Promash can do it all for you automatically.
First you need to setup your defaults eg metric units and what you default boil time, efficiency and evaporation rates are etc.
Then there are two parts to Promash.
You input your recipe with all your ingredients etc and save it.
You then start a New Session (Option on the front of Promash startup screen) and choose the recipe you saved in the previous step.
Then it will work out automatically how much HL for the mash etc. You can tweak the sparge amount to get the final volume you want dependant on any loss of liquid due to dead space etc. Once you enter all your dead space from your equip you can also save those as default.
Then on any subsequent session you just have to change the sparge litres to get the final volume you want. All the rest is done automatically.
Beers,
Doc