Importing Modules that use MultiProcessing Python

I am looking to use the multiprocessing module to speed up the run time of some Transport Planning models. I've optimized as much as I can via 'normal' methods but at the heart of it is an absurdly parallel problem. Eg Perform the same set of matrix operations four 4 different sets of inputs, all independent information.

Pseudo Code:

    for mat1,mat2,mat3,mat4 in zip([a1,a2,a3,a4],[b1,b2,b3,b4],[c1,c2,c3,c4],[d1,d2,d3,d4]):
        result1 = mat1*mat2^mat3
        result2 = mat1/mat4
        result3 = mat3.T*mat2.T+mat4

So all I really want to do is process the iterations of this loop in parallel on a quad core computer. I've read up here and other places on the multiprocessing module and it seems to fit the bill perfectly except for the required:

   if __name__ == '__main__'

From what I understand this means that you can only multiprocess code run from a script? ie if I do something like:

    import multiprocessing
    from numpy.random import randn

    a = randn(100,100)
    b = randn(100,100)
    c = randn(100,100)
    d = randn(100,100)

    def process_matrix(mat):
        return mat^2

    if __name__=='__main__':
        print "Multiprocessing"
        jobs=[]

        for input_matrix in [a,b,c,d]:
            p = multiprocessing.Process(target=process_matrix,args=(input_matrix,))
            jobs.append(p)
            p.start()

It runs fine, however assuming I saved the above as 'matrix_multiproc.py', and defined a new file 'importing_test.py' which just states:

    import matrix_multiproc

The multiprocessing does not happen because the name is now 'matrix_multiproc' and not 'main'

Does this mean I can never use parallel processing on an imported module? All I am trying to do is have my model run as:

    def Model_Run():
        import Part1, Part2, Part3, matrix_mult