hey, i was just about to code up something like this (viz., wavetable selection by frequency) and thought i would search here first. excellent!
maybe this is useful: a small and simple tool for converting soundfiles to the SuperCollider [value, delta] format, resampling to arbitrary length, &c:
more to the point, i just added a feature that also produces sucessively-bandlimited copies of the input wavetable. haven’t really tried it out yet, but should be appropriate for preparing WT files for use with a synthdef like this.