The fastest way is probably a medium-sized flight school which has the staff, equipement, and flexibility to load up your schedule and get it done. You are basically looking at two flights (or sims) per day, 5-6 days/week.
A small school may not have the resources to consistently support that pace, and the large academies always schedule according to their best interests at the moment...a student who has already signed up is just a cog in their machine.
With a comm AMEL, you could then get a job at mesa. That's probably the fastest way.
But life at a bottom feeder like mesa is a whole 'nother topic of conversation...if your friend thinks one regional is just like another, he is mistaken.