Is AVIsynth able to interpolate frames? Is there a plugin for Virtualdub?

I'm trying to slow down some footage (of a car wheel turning) to around 300% of it's original duration. Most programs simply duplicate frames, but I want frames to be interpolated inbetween the real frames for it to be smooth (this is going to be the background of a DVD motion menu). After Effects has duplicating as default, although it's help file mentions that it has "Enhancing time-altered motion by blending frames", but does not say how to enable this.