It's actually very easy, but there are some caveats. First, decide if you need GFCI. I highly recommend it, but it depends on what it's used for. For a brew rig, I would not install without. You may want to buy a GFI breaker instead of GFI outlet (do they make GFI outlets?)
Second, you'll need to know how much current you are going to draw. I think 30A would be enough, but without seeing your plan, I'm guessing. Assuming 30A, then install a 30A double pole GFI breaker in the panel and run wires out box like a normal outlet, except you will have 2 hot wires instead of 1. (You'll need the appropriate wire to handle 220V and 30A, but I don't know what the number is off the top of my head...)
As far as the GFI wiring, I'm not experienced in that, so you may want to Google some examples. Normally you wire the bare ground and the white neutral to a bar in the panel, and then to the appropriate places on the other end.
As normal, please disconnect the juice to the main and watch your hands and tools when working with the power panel. There is always a risk involved if you are not experienced, but I understand that paying an electrician can be very expensive for such a simple thing, so if you just don't want to pay a real electrician, at least find someone you trust to know what the heck they are doing, or be very careful.
You could always submit your idea as a drawing on this forum. There is a small chance you will get an answer without the post being ground into a flame war on safety or electrical code.