Two PSU One PC. Possible?

I have an extra 250W power supply (came from HP) and a GTX 460 lying around. I have a 600W (Generic crap that wont blow unless I add a GPU) in my system right now. Is it possible? How will I make the 250W power supply give juice to the graphics card alone?

Dual PSUs are pretty common. I use dual PSUs on my rig.

You can use one of these.

Amazon.com: Vantacor Dual PSU Adapter Cable 24 Pin 2-way: Home Audio & Theater