This seems like something that shouldn't be done in general, so doesn't need a language fix--but if you for some specific reason need to do it all the time, just write a function for it:

    def _postimport(mod, names):
        g = sys._getframe(1).f_globals
        for name in names.split():
            g['_'+name] = mod[name]

So:

    import thingy
    _postimport(thingy, 'spam eggs cheese')
    use(_spam, _cheese)

Of course you can wrap up the import and _postimport in a single function:

  _magic_from_import('thingy', 'spam eggs cheese')

Or use MacroPy to make the syntax nicer.

Or, if even that's not good enough, write a simple token-processing import hook that finds "_import" tokens and converts them to calls to your wrapper function.

Of course the farther you go down this path, the less readable your code becomes to someone who doesn't know about your function/macro/hook, but if there's really so much boilerplate that it's getting in the way, the tradeoff might be worth it.