Hello, I have many years experienced with asterisk and digium hardware. Normally setting this up will take about 3-4 days, however all you are looking for is documentation, step-by-step procedures, which in my history takes longer than doing the actual task, as I would need to think of potential forks in the roads, with solutions.
I've also been properly trained in corporate style documentation procedures, which is an asset for your project.
As for all voip projects I do, I offer free 30 days support (email,IM) after completion.
We have business references if needed.
Thank you.