Old 401K with both pre and after tax to roth

Mat and Mark,
Thanks for the great info!  Podcasts and books are amazing.
     What is the best way to convert old 401K’s that have both pre-tax and after-tax monies into a Roth account?
     How will this transfer affect the withdrawal from the Roth in the future?  (will I need to wait 5 years?)
    Can I start the Roth account, and then turn it into a self-directed Roth (with an LLC) at a later point in time?
58 years old.  Semi retired.  Work part time/seasonal currently.  Alaska/north slope (no income tax).  Trying to convert to ROTH