it took me exactly 5 minutes to learn how to drive a manual transmission.
Getting good at it took much longer, especially when I only drove my car on the weekends.
Just my 2 cents, there is no better experience of driving a six speed manual transmission whith a 250 HP mid engine behind you. The pure drving experience is: Shift, throttle, steer and brake
I really am opposed to anything on a sports car that compromises those basic skills. Mercedes now has cruise control that will brake and accelerate for you.
try posting an ad on craig's list in your area under services. I'm sure someone would gladly teach you how to drive a stick shift for $50.
p.s. something that helped me was to deliberately stall the car a bunch of times to get used to the limit of how much you can lay off the clutch pedal before the engine shuts down. Learning to drive a stick shift is allot like racing, you have to be comfortable with what you are doing in the cockpit first. Thinking about what you are doing and trying to execute at the same time is very difficult unless you are at ease. Oh and get in the habit of always pusing the clutch pedal all teh way down before shifting. Not doing so "bozo clutching" will reduce the life of you clutch.