These things have been around a while and my apologies if they have been previously covered here. I just got a couple and set one up to do some testing. Basically they work quite well, and the price is right at about $7.50 each. Here is a picture:
Each relay channel is individually selectable for high or low direct triggering. Plus each can be individually turned on or off with the remote, as long as its line of sight. You can also flip them all on by hitting 9, or all off by hitting 0. My plan is to try these out for controlling town lighting, individual accessory power, etc, when I get around to it. 
Since the IR part is line of sight and you would probably want to set the board under the layout, the IR receiver board would want to be unhooked from the main board and mounted somewhere inconspicuous. It should be easy enough to hide since its only 1-1/8" wide, and the only part that actually needs to be seen is the lens of the IR led.
The receiver board is soldered to the main board with an angled 10 pin dupont connector. So this would need to be cut out and replaced, then connected with a 10 wire tether to the main board. (I might try the solder sucker first and see if that cleans it up well enough to get them separated.) Fortunately there are lots of pre-wired dupont ribbon connector options around.
I also fixed up some awkward wording in the manual, and its pdf'd below. 
Rod
