Any way to above having them change settings in the Gruntfile?

E.g. Having the Gruntfile accept additional browsers to run via arguments?

    $ grunt default --browsers=IE,Chrome,Firefox

And also would be nice to:

    $ export SAUCELAB_USER=ibolmo;
    $ export SAUCELAB_SECRET=MOOTOOLS_ROCKS;
    $ grunt sauce --browsers=IE,Chrome,Firefox