Afaik, you can't change a single thing in a map in SFM, including dynamic props (you'll notice that spawn doors and control points, all prop_dynamic, are gone when you load the map. If I remember correctly, there's an option to turn them back on when you right-click on the 3D viewport, but you can't do anything with them). Your best bet would simply be to have that wheel model loaded separately into SFM, put in in the position where you want it and animate it by hand.