I think the speakers would have to be pretty loud to hear them over the wind noise. I think it would only be worth it if you did not wear a helmet.
I seen a few in myrtle beach that had a speaker system hooked up and it turned heads, if it is what you want, you should go for it.
It should be simple to hook up. Just take an IPOD deck with built in speakers and disassemble them. You would have to fabricate the place to mount the speakers. The spot under the handgrips seems to be an ideal spot.