Mega necro bump, but I figured I would chime in as there's not much info about the Exceleena 2. I have one of these and rotated the monitor for the first time on Friday. It's quite easy to do solo. The monitor frame is secured to a plate with four bolts. That plate fits into a sort of guide/groove mounted on the back door. There are two handles on the front monitor bracket. It's not as simple as an Egret 2, but the weight of the monitor is well supported even if you have to place it down mid-rotation. To sort of 'engage' the hinged mech and allow the guide to move freely in the bracket you have to pull out towards the front while simultaneously rotating. All in all I did it myself in a minute.
Like others have mentioned above, vert games will be incorrectly orientated by default. A previous owner of my cab had changed the monitor's physical orientation so that vert games will look correct. As a consequence, horizontal games are flipped for me. You can correct this on most games by flipping the video via DIPs or the test menu. Look for 'monitor flip' or 'cocktail mode' or something similar. A side effect of the location of the rotate mech is that the back panel seems to be inaccessible. If you're trying to adjust convergence or something on the chassis it seems like you'll have to take the whole monitor out and run video to it externally from the Exceleena.
It's decidely low tech compared to the Taito mechs, but it works.