How to pass unpicklable variables to multiprocessing pool?

I've been searching for days but I can't figure out how to pass an unpickleable variables to a multiprocessing Pool. Is it even possible?

I'm new to multiprocessing and I may miss a few concepts here and there. However, I tried to reproduce some basic examples in my case where I'm trying to parallelize an extraction of an Abaqus result file. For this extraction to work, I would need to pass each worker a "step" object, that is a not picklable Abaqus object, as well as zip files open for writing. I've tried to use several functions of the multiprocessing library but it looks like this pickling is a showstopper for me.

Another constraint I have is the use of Python 2. Indeed, I must use the Python distribution embeded in Abaqus and they've switch to Python 3 only in the very latest version I'm not using yet.

Could someone share an example of multiprocessing.Pool with unpicklable variables? I don't care sticking to multiprocessing library if there's another one allowing me to parallelize the workers in my case. Just keep in mind I can't modify the Python distribution in Abaqus and I may not have access to exotic libraries...

EDIT: Here is a simplified code of my approach

from odbAccess import *
import multiprocessing as mp

def extraction(step):
    # Do something with "step"

if __name__ == '__main__':
    odb = openOdb("path_to_my_odb_file")
    pool = mp.Pool(2)

    pool.map(extraction, odb.steps.values())
    pool.close()
    pool.join()

I get the error:

pickle.PicklingError: Can't pickle <type 'OdbStep'>: it's not found as __builtin__.OdbStep

I've changed the package and I'm now using threading instead of multiprocessing. More or less the same syntax and much less limitations.