I haven't had luck with mouse, but you can actually connect a bluetooth keyboard to the Apple TV. I use a little handheld unit from Rii and it works great.
For mouse, if you have an iOS device you can use the "Remote" widget on your phone as a mouse, and it works in the Moonlight client well enough to click through prompts etc.
For mouse, if you have an iOS device you can use the "Remote" widget on your phone as a mouse, and it works in the Moonlight client well enough to click through prompts etc.