Okay . . .

/bind F6 throttleset 0.25

Makes it so that F6 sets the throttle to 0.25

With that, you can bind the F-keys to throttle settings.

You can go backwards with throttleset -1

With Logitech's "Zone" feature, this goes a long way to being able to control the throttle of the ship via the joystick's throttle. I have the bottom zone set as -1 for reverse, then the rest set from 0 to 1 in 0.25 increments, which I think reflects the keyboard controls.

BTW, when using the Logitech Profiler the key for full impulse should be recorded as a command, including recording pauses - otherwise, there seems to be some bug that resets the throttle.