As for “analog” trim wheel you can check if it’s possible to adjust its sensitivity via controls options (it might be not).
FSUIPC is basically the same controls options, but with more precise settings, although I can’t confirm whether it supports trim wheel periphery.
I personally use buttons as they provide the smallest step possible when trimming; still the whole process in unnecessary difficult in the sim (while it’s literally meant to ease things up). There’s a scripot for auto-trim and FSUIPC I’m planning to test, but as for now…