Are you talking about the slingbox or your cablebox? The 350 definitely comes with component/composite outputs.
If your cablebox has no component/composite outputs, you won't be able to connect and stream from your 350. Not unless the cablebox comes with HDMI output. In that case, you can use an HDMI to component adapter. However, that would be extra money to get. You might want to consider getting a different cablebox from your cable provider that comes with component outputs.