Hybrid crossfireX

My question is this, I am running a Gigabyte mobo ga890-ud3h with 4290 on board graphics and a XFX one HD 6750 can I run this setup hybrid crossfire? would it be beneficial to do so? And if it would help how do I do it? The motherboard supports it but has no option for it in the AMD catalyst. Any feedback would be great. Even if your going to call me an idiot for wanting to try it. Have to learn somehow. In my head two gpu's are better than one but I am still learning so be gentle.

AMD 965 B.E. O.C. to 4.0 ghz
Corsair H50 cooling it.
GA890-UD3H MOBO
4gigs ddr3 10666
XFX One HD6750 1g gddr5
600 watt cooler master psu