Not sure I really know what your specific question is on the hardware installation.
Just make sure your cabinet is not too tight and the projector has normal air flow and the vents are not blocked, that is the most important thing. Since your projector has lens shift, you don't even need to worry about lining up the projector lens to the screen (just get it ballpark). Your projector can automatically move the projected path both vertically and horizontally with LENS shift. I think the RS20 has the lens shift on the remote itself and/or the menu, so just use the motorized lens shift controls to line up the picture to the screen.
Note that your question is an almost impossible to answer without knowing what hardware you already have and what your specific plans are for setup (cable box?, Bluray player?, UPS?, HDMI switches?, other cables, where stuff goes in your room, etc...).
Read this thread and specifically the 5th post down that I posted, and maybe this will help, I am not really an expert but I have shelf mounted a few projectors in my day...http://www.avsforum.com/avs-vb/showt...eration+remote
Here are some images of my own setup that might help or give you ideas??
(scroll down past the initial images to see the actual SETUP images)http://www.flickr.com/photos/45387881@N03/
First, to ensure lamp life in case your power goes out, it is recommended that you plug a projector into a UPS power device, these can be found at newegg.com. You should only need 350 watts or so, just pick one that has decent reviews (any 350+ watt one should work). Personally I would shoot for 450 watts or higher just because the battery will last longer. What the UPS does is allows your lamp to cool down in the case of a power outage. Some UPS also have voltage regulation and cleanup to maintain a better electrical signal.
UPS section of Newegg:http://www.newegg.com/Product/Produc...ue&Order=PRICE
If you have a volt meter, make sure your electricity is fairly clean (around 120 volts, but even a 10% to 15% variance is generally ok, anything more and I would certainly buy a UPS with AVR built in (automatic voltage regulation).
If you have 3 or more devices to hookup to your projector, then the first thing you will need is an HDMI switch (about $40), you can get one at Monoprice.com, just type HDMI switch in their search box. Make sure the switch specs say 1.3b on it to ensure it is one of the newer models. Depending on how many devices you have and how far you will be putting the cable box, bluray player, you also need to buy HDMI cables. Make sure to get decent and thick HDMI cables if you are running them more than 12' long to the switch.
If your putting the AV devices behind you as it sounds like, then you'll need a Remote Extender so that your remotes can still work when your A/V equipment is behind you. For this I recommend the Next Generation Remote control extender with extender eyes:http://www.amazon.com/Next-Generatio...6581074&sr=8-1
For the extender EYEShttp://www.amazon.com/Next-Generatio...6581155&sr=1-1