Hope you forgive a newbee to put it's 2 cent in here 
played a little on indirect modulation. There is indeed a chance of env3 to modulate filterbank frequency - weird yes - but not impossible - only the result was not really a great hit.
Start from an -INIT- patch ... and set the filterbank to comb ... than go to the modulation matrix ...
slot1:
- source: env3;
- dest1 -> slot4-dest1;
- dest2 -> slot4-dest1 (yes a second time - it does not work with one only)
slot4: source:ModWheel (modwheel cranked up);
- dest1->filterbank frequency
The amount of ModWheel controls the amount of filterbank frequency and this amount is controlled by slot1 destinations ...
Now get the sliders of the destinations in various positions and you should hear that the comb filter frequency is indeed modulated according to env3 ... BUT ... there is a gritty background noise coming along with this settings and I did not get rid of it. 
It seems to depend on the amount of the sliders in slot1. There must be going on something inside the modulation path that is not working properly. A bug 
