How can I pass a Mel string variable into a python call from within a mel script ?

so I want to do something like this ... but this doesn't work:

string $myString;
string $myList = python("myString.split(':')");


Studio where I work cannot move totally to Maya python, but I would like to take advantage of python's string, list, and re methods from within a mel script. I'm wondering if anyone out there has done something similar. I thing I need to precede with another python call to create the python string object named myString .... but still can't get anything to work ...