I've given it some thought, but I guess also checking whether or not it is feasible should be done.
I will inspect the sources surrounding users and sessions / cookies.
This is something I've implemented at the early stages of development for my own projects, but haven't looked at for something of this magnitude, mainly because of the time required to research how it all ties together and works... at the top of my head it will (if not pre-existing) require source modification and additional tables in the database, essentially what it will do is read the data into your session and apply when logging in or re-visiting with a prior session still live.
Sounds easy enough, yeah? ;P
