Is it Possible to Change your Associated G-Mail E-mail Address?

Like many, I am sure, I created my channel under an e-mail address I'm not too ecstatic about. It was my old channel name before I changed it when I was given a free custom URL.

I would like to change the e-mail address associated with my YouTube channel but I am getting mixed research when I search how to do this. Some tutorials say you can create a different GMail account and add it as a managing account and then set it as primary (but I don't even have the option to add a g-mail account as a manager for my channel). Some say to create a different Google+ account and transfer your channel there (but I can only transfer it to pages owned by my current g-mail account so I don't know how this is possible) and others simply say it is not possible anymore.

Can anyone shed some light on the possibility or lack thereof? If it is possible, how can I do this?