I've been considering a second Pest actually. I think they are really good value. This sort of thing would work on a Taiga as well but the Taiga's folders aren't patchable so you would have to use an oscillator.
I don't have a Keystep so I'm not sure what it's setting options are. You would want it set to a 5V trig and 1v/octave CV scaling. CV goes to pitch input and trig/gate can go to the dynamics trigger input. If this doesn't work you can try setting the sequencer to external clock and see if your gate will advance the sequencer. You can also play the Pest from the keysteps midi out. Just make sure it's set to the same midi channel.
I think the West Pest is best for short plucky sequences or growling bass sounds. You can try running other types of audio through the wave folder with the Pest on Hold mode.
