Frankly, the best thing you can do (which I tend to do) is just stay in character. Yesterday we had about two hours where the general chat was totally IC. I found some great RP interaction when I was just hanging out in the nexus room. If you stay in character, people will play along. Non-RPers might even play along. I've had some great RP sessions in this game so far.
Treat the public chat channels such as General as an open comlink. Sure, non-rpers get on there too, but you just deal with it, ignore it, or incorporate it.