I recently put in a "trickety trock, trickety trock" section in a song involving a train journey. I was in 6/8 (though you could do it in 3/4) and I just used snare with alternating soft/loud beats; 1234 - - 1234 - - snare hits on 1234 rests on - - (5&6). In 3/4 it would be 1231 - - 1231 - -
I got a sample of steam noise from freesound.org as backing and the final result was very realistic for a the noise in a steam train carriage.
you could do it in 4/4 but it won't line up with the bars so neatly. I was using AD2 where there are a variety of snare sounds. In SI drums there are a variety of sounds and you'll need to shape the EQ to get the sound you want. Hope this helps