Well after hours of tinkering and some ingenuity, I got my Blox Limited 490g Electric Blue to fit without the boot be snug at all. What I ended up doing was buying two 3/8in rubber grommets from home depot and sliding them all the way down below the thread, then I placed a 3/8in a metal washer (which I dremel sanded to fit over the threads) on top of the grommet. After putting boot on and screwing in the knob I got a great fit and the boot doesn't slide at all.
I love the look and feel of this knob, goes great with all the blue accents lighting and such in the car :)