2000 328i trans position switch

I see traces of fluid on the tranny position switch. RealOEM indicates that there is a shaft seal ( see part #2 http://www.realoem.com/bmw/showparts...36&hg=24&fg=15 ). Can someone tell me how to replace the shaft seal or how to remove the trans position switch? Do I need to drop the transmission to do this? Appreciate your help in advance.-Peter