What kind of shifter is this? The entire kit or just the lever?
If it's just the lever it shouldn't take you more than 30 min with the proper tools. You will need to get under the car though to remove a "C" clip which connects the lever to the rest of the transmission.
Removing the shifter boot, all the rubber and crap is easy. Actually removing the shifter lever is next to impossible. You will need a special angled screw driver which is almost 90 degrees at the bottom. This will be used to yank the shifter lever out. After you've done that the hardest part is over, everything else is pretty much straight foward.
'02 C32 AMG / '07 C280 / '07 CLS550 / '15 JKU Rubicon