There are 12V wires running all around the TT, would think that one would be available to splice into. Removing the IOTA Load Center is a major headache on some models, especially when the converter/charger is mounted to it.
I have a 2005 Eagle and it sounds like you have the same unit I have. I believe what you are referring to is the IOTA ILC 3045 (Load Center) with the breakers/fuses behind the black smooth cover. The actual IOTA DLS Converter/Charger is mounted on the backside of the load center
I have had mine pulled out a couple of times, and it was a real pain. The black frame has the just the center screw to remove that you mentioned, and yes, there are plastic tabs around the black frame that have to be dealt with (see pic below). If you work at it you will find where the tabs are to push on...., I had one break the first time I removed the frame a few years ago. Also, there may be a large fuse that needs to be removed or the frame won't clear it.
Once the black frame is removed, you will find the four main Load Center mounting screws. Be careful removing the load center, there a lots of wires and their lengths differ and may not want to come all the way out with Load Center. Take pics so you know what goes where.
IOTA ILC-3045: http://www.bestconverter.com/assets/...LS/ilcmanl.pdf AND http://store.fretzrv.com/fretzrv/inc...ew&fileid=1597
Hope this helps.