>>>If anybody has upgraded from a 3 speed sturmey archer to a multi-speed gear set for touring on the Brompton folding cycle, would they possibly have any information about how to accomplish this?<<<<<

I know some people who changed to the six speed but that won't make it a touring bike. Probably the only company making true touring bikes that have folding capabilities is Bike Friday. The six speed Brompton does not give you enough gears for touring and the geometry and small size is less than desirable.