Time Warner Cable Box



I have a Samsung 3050 HD Time Warner Cable Box that I just installed. It's connected to my tv, that only has one HDMI open slot. The cable box us connected and works, but I wanted to know if there is a way to hook up my Roku box to make it work too.
It could depend on the generation of the Roku box. The Roku 2 has an A/V port but the 3 does not. If it does have that port, you could use composite cables but allegedly, it may have to be a cable bought through Roku because the port is proprietary.