In the past I have tried a number of settings on the warthog hotas throttle slew control (saturation, gain etc.) axis to accurately control shkval aiming (not only KA-50, but also su-25T etc.). However, I never got it to work the way I wanted...
The set-up which I use now is to also map the coolie hat to the shkval discrete slew (i.e., the ,./; key-bindings). Coarse aiming is done by either TrackIR HMS or warthog slew control, then refine by using the coolie hat. Works like a charm!