sorry to sound like a dick, but it sounds to me like you guys have no idea how most of those C64 percussion sounds are actually made?
it's pretty much a "wavetable", playing back different waveforms and parameter settings in succession at very fast speeds. this screenshot of the '38911bytes' VST shows it pretty well (similar to how C64 trackers do it):
so, this is pretty much impossible on most any normal analog synth.
BUT...
(bare with me, i haven't been up on the A4 since release)
the A4 has the ability to change patch settings per step. i don't know if it's possible, but if there's any way to use an LFO or other modifier to trigger patch changes *faster* than per step, then it might be possible. i was thinking about this when the A4 came out (probably mentioned it here or elsewhere as well). another thing might be to multiply the tempo of an individual track (is this possible?) to get something like this going.
let me know if this doesn't make sense, i'll try to explain it a bit better.
also - the C64/SID has nothing to do with "bit crushers", "aliasing", or anything of the sort (unless playing back samples on it, which isn't the case here). it's pretty much an analog synth on a chip.