JVC has a head unit with circle surround, as does Panasonic. That will probably be the easiest and most cost effective route to go.
You need 4 speakers... that will give you a phantom center... and you need a sub.
5 - channels of amplification.
Ideally, front speakers should be installed in kick panels for a better phantom image and better front sound stage.
Ideally, rear speakers should be identical to the fronts (you would not purposely buy a different front right and front left speaker, so why should rears be different?). But second best would be different size speakers, if you need to, from the same line. Third best would be just mids in the back that play at least to around 5,000 hz. Tweeters are not absolutely necessary, Dolby rear channels roll off at 7K anyway.
Kicker SS components would be the best choice.