Sure - just unscrew the cable fromthe speedo - the inner cable will come right out the end. Grease it as you slide it back in. Turn it to get it to seat mack into the tranny at the end (you may have to unhook it under there and do it manually if it doesn't cooperate).

However, that's usually the input bearing on the speedo = and it is far more difficuly to get oil into that. Generally, you'll have to take the speedo cluster out, set it on end, and work oil into the input shaft bearing.