That sounds very weird. After connecting the Slingbox Classic with the TiVo using the composite cables (red-white-yellow) did you change the settings in the setup? I recommend that you connect the Slingbox in that way and after that Reset the unit and run the Setup Assistant again
You have to disconnect the HDMI cable.
Then run the component to your TV and the Composite to your Slingbox.
I don't believe there is a Premiere remote code or skin available yet and may never be for a SBC, but there is a user-created one here you can try.