The transmitter is wired. You may be able to rig something up from Radio Shack to battery power it, but it would fail your cosmetic requirements.
You can hide the RF transmitter since the 890 does not need line-of-sight between the remote and the base. Just hide the base and run the IR emitters to your component's IR receiving eye. The wires are generally ran under the component and come up and stick to the IR receiver. You would hardly see them if you take your time and do it right. You could also rig it so that the IR emitters aren't attached, but near the component to be small IR flashers. Some people have luck with them right below the component.
You can hide the RF transmitter since the 890 does not need line-of-sight between the remote and the base. Just hide the base and run the IR emitters to your component's IR receiving eye. The wires are generally ran under the component and come up and stick to the IR receiver. You would hardly see them if you take your time and do it right. You could also rig it so that the IR emitters aren't attached, but near the component to be small IR flashers. Some people have luck with them right below the component.
