Original from the forum. Just reposted here because hard to find.

First of all, the object must be exported as EDF in the track folder.

Then, the SCR file of the track must be edited or created ( using the folder name as filename ).
Example SCR file that adds a rotating object ( obj2 ), using “Nevada_18” as the base:

obj0
{
flag = 1
name = *flag_country_big.edf
paint = flag_usa.pnt
data = flag.cfg
pos = 98.09, 25, 55.93
}
obj1
{
flag = 1
name = *flag_country_big.edf
paint = flag_usa.pnt
data = flag.cfg
pos = 98.09, 25, 76.93
}
obj2
{
name = filename.edf
rot_axis = 1, 0, 0
rot_time = 5000
pos = 100, 10, 60
rot = 90, 0, 0
radius = 10
}

The three parameters of “rot_axis” and “pos” are X, Y, Z where X+ is right, Y+ is up and Z+ is forward, looking at the map in TrackEd.
“rot_time” is the time, in milliseconds, to complete a full turn.
“rot” sets the local pitch, yaw and roll rotations of the object.
“radius” is the radius, in meters, of the turn. Zero means that the object rotates around itself.