in a word yes. are you supposed to do it now with it in the vehicle, my professional advice is no. the proper way would be to take it back out and lube the input shaft, but i'm sure that someone on here will tell you just to spray some crap on it and let it ride, all i can say is that if you get some on your clutch then your f'd.
You should have. It says to do it in the haynes manual and they have a reason for doing so. I greased mine and it hasn't chirped since day one (1.5 yrs ago).
Scott