skimage.transform.warp calls scipy map_coordinates dosen't it? I believe that does not use the same interpolation method as the IDL routines. I wonder if that could be worked around though.
In case of the PolynomialTransform it will always use map_coordinates, for linear transformations with a transformation matrix, it uses a much faster internal Cython implementation for order < 4.
If you set order=3 it would use the same interpolation method as IDL, but you do not have the option to manually set the scaling of the sinc function. But it uses a sensible default for that.