gistfile1.txt

class _ImporterProxy(object):
    def __init__(self, mod):
        self.__mod = mod

    def __getattr__(self, meth):
        try:
            ret = getattr(self.__mod, meth)
        except AttributeError:
            ret = _ImporterProxy(__import__(self.__mod.__name__ + '.' + meth, fromlist=['__trash']))

        self.__dict__[meth] = ret
        return ret

    def __repr__(self):
        return repr(self.__mod)


class Importer(object):

    def __getattr__(self, meth):
        ret = _ImporterProxy(__import__(meth))
        self.__dict__[meth] = ret
        return ret

i = Importer()

if __name__ != '__main__':
    import sys
    self = sys.modules[__name__]
    i.__self__ = self
    sys.modules[__name__] = i

gistfile2.txt

import importer as i

i.whatever_you_want