Which Sling do you have? If you are using a Solo then when you change a channel it will change on the TV as well. If you are using a Pro, Classic, or Tuner then you can set it up using the coax input and not disturb the person watching TV.

Slingbox Pro Slinging Comcast Analog and HD via Comcast Internet using AirLink Powerline adapters; Slingbox Classic Slinging Sunddenlink Analog and HD via Sunddenlink Internet, using netgear powerline adapters. Both use Motorola DVR boxes