OK, I live right off of route 27 in Clermont (my most dorect route to WDW from home) and work literally 200 feet from the 429 where it meets the Turnpike. I know this are very well.
(and to the above poster, getting off in Clermont and taking a back road to the 429 is longer and saves you nothing.)
To the OP, here are specific directions:
Take I-75 to the Florida Turnpike, which is exit 328.
Take the turnpike southbound to exit 267 onto SR-429 SOUTH.
Stay on that about 10 miles until you see the signs for "HARTZOG ROAD/WALT DISNEY WORLD"
Get off that exit and at the bottom of the ramp take a left towards Walt Disney World. Follow the road all the way to the end, and you will be right next to CSR on Buena Vista Drive.
Anne