Hi there, it pretty much depends on what kind of halos you are talking about.
If you mean the halos that you install into the stock headlight assembly, installation of those means you will have to disassemble your stock headlights first, install the halo rings inside, then assemble the lights back (it's better to silicone them after that to prevent moisture), and then to hook them up.
If you are talking about the new headlights that feature built-in halos already, the process will be way simpler. Just remove stock lights, install the new ones. The connectors will be pretty much plug-and-play except of the halo ring wire. Usually people wire those halos to DRLs with a set of connectors. Here's the complete instruction on how to install the lights. Here is the link to the complete selection of halo headlights we carry for the 2012 Challenger.
Hope this helps!