do you think theres a hack that lets you
no there's no hack afaik.
crossfiring them is impossible because they are two very different cards. mostly because amd doesn't allow it. if they did, no one would buy their new high end card, instead people would recycle old cards, crossfire them with new entry level cards for higher performance.
use either one of the cards.
or get a more powerful single card like 6870, 6950, gtx 560, 560 ti, 570. or wait for the upcoming radeon 7000 series cards or nvidia's kepler 6xx/7xx series. they'd be much better than the 4850.