With money.
Have money, Contact buildhouse, Work out a deal with buildhouse (either to possibly rebadge/small changes to one of their "Stock" drivers Or to completely custom built a driver you had designed for you/your purpose.
Have drivers built, have them shipped to you OR some buildhouses may also take care of order shipping. Ship them to dealers or to customers from website sales and such.
I would expect the minimum funding you would need for this would be roughly $10,000. As if you order to few of drivers then the cost per unit skyrockets and you cannot compete wiht other larger companies that alreayd have started.
For instance on the TC Sounds webiste they state that "Please note that we are a high volume original equipment manufacturer and require a minimum of 50 units per order for our standard drivers."