Fortunately the CT uses a standard mounting wedge. To remove the factory mirror simply push up and out. The Gentex slides right over the existing wedge.I'm not familiar with the Gen45 but I'm just curious how you are going to install this. I'm assuming you have a regular rear view mirror and wanted to upgrade with this. Do you have to remove the original mirror and use the same mounting post? Or this new mirror came with it's mounting post so you have to remove the existing post from your windshield?
Back to your question, I'm sure there's some room behind the ceiling lights to hide whatever wiring that came with Gen45. I read some folks have wired their radar detector through the rear view mirror so it's possible for you to do the same.
Good luck with your mod.