I don't see why not. I don't know exactly what the plug or wires on the fan look like, but often enough they are the same red, yellow and black arrangement you'll see on most other items, i.e. molex connectors, sata connectors, and so on. Used to be not that uncommon to see an extra fan or two hacked into a case by clipping the end off of something like a floppy power connector and using it to power a fan directly if it had a motherboard connector, but no more places on the motherboard to plug it into. Should just need 12v and ground.
If it were me though, I wouldn't just randomly clip anything though, I'd get something like a sata power extension/splitter or similar clip that, that way you don't permanently chop your power supply.
Here is a page that shows you the color coding on power supply rails and their voltages. Pretty uniform.