Having tries to target two of these environments at the same time I can safely say the if you have to use a database etc. you end up having to write unique code for that environ
If you do find you need to write unique code for an environment, use pythons
import mymodule_jython as mymodule
import mymodule_cpython as mymodule
have this stuff in a simple module (''module_importer''?) and write your code like this:
from module_importer import mymodule
This way, all you need to do is alter module_importer.py per platform.