I have prepared a modding walkthrough document here:
These are the main threads outlining what is presently the most popular and well-documented path to mod your c64 mini:
I had references to these on the Hardware Compatibility page here:
This is a method I'm still pondering. I shared some thoughts on it via twitter:
I still haven't seen it through yet, so if someone wants to beat me to the finish-line, they're most welcome to :)