For those people that have a Saitek X52 (single throttle) plus stick, I've found a way of getting the tiller axis to work (using FSUIPC):
1) Locate a spare rotary wheel (ie. not one that's already being used by the prop control). It needs to have a centred detente, so the slider won't do.
2) In the Majestic CP, set the tiller axis to "spoiler". Do this prior to starting FSX - or reload the aircraft if in FSX.
3) With a Dash8 loaded in FSX, open up FSUIPC and tick/use a "profile specific" profile - in case you use the spolier axis for regular spoilers in other aircraft.
4) Set your chosen rotary axis (or twist-grip rudder axis on the stick if you're using rudder pedals) to "Spoilers" in FSUIPC axis management, then check that it works OK in "Axis Calibration". You may need to check the "Reverse" box.
That's it!
When taxiing, keep 5 degrees of flap to get full movement. If you toggle the steering switch, you should find the tiller works as advertised and neither ailerons nor rudder are moved by it.
I'm no FSUIPC guru, but I found this appeared to be relatively simple to set up.
Adam.