Before the LG M2794DP I had in my office/gameroom a LG L1915S monitor - which was great btw. I could connect my Xbox 360 via a XCM VGA Box and play perfectly well, except for the obvious fact that it was weird switching from a widescreen to a standard one.
The XCM e-setter is an ingenious little gadget which resembles a pocket calculator. What you do is plug it to a USB port, then press the keys and define the output and resolution that you want. From what I understand, it sends to the PS3 the same commands that you would do if you actually had a display and configured the settings with your gamepad. Very simple, very effective and it is upgradeable. As a matter of fact, before you use it for the first time you must update it after visiting the product's homepage.