ALTSHIFT_TAPS megafunction in Quartus II 9.1

What device are you targeting? It should be in there.

Note that Quartus synthesis does an excellent job of finding shift-registers and inferring altshift_taps, so there generally isn't any reason to manually instantiate the megafunction. The one thing to avoid in the RTL is a clear on the shift register(asynchronous or synchronous) since the memory block can't have its contents cleared in one cycle. I think altshift_taps inference has a way around this, but it's probably better to avoid the clear if you can(and most shift-registers can).