The first post has an updated version of firniture that no longer requires setting taps manually.
[edit] The "noalias4" kernel has been updated, and is now significantly sharper
Additionally,
here is a sample of the lighthouse image interpolated 4X by the "noalias4" kernel. Compare it to
this interpolation using the standard spline36 kernel.
Keep in mind that these kernels are intended to be used for downscaling, or relatively small resolution adjustments. The comparison is done on upscaling because it makes the differences much easier to see. As should be clear, the "noalias4" kernel has very very good alias suppression, but is not quite as sharp as other kernels.
Each of the provided kernels is intended to fill a niche for which there currently exists no satisfactory solution in Avisynth. Obviously, using a low aliasing kernel on a blurry source would be a bad idea, but its great for those times when your stuck with an over-sharp source that is tripping up normal downscalers (or format shifters, etc.).