Well I finally made it. 
I left the bubble on Jan 2 and made my way out to 6666:66:6666 for the start of my trip to the core. I then ran what I'm calling Route 66 all the way in to 6666:66:25900 in a (pretty) straight line. I don't think I wandered more than a few light years off the route.
Then I turned sharp left and followed the X:66:25900 line in to straight above Sag A, and then a couple of jumps down and I was HERE!
Route 66! A road to the core for the spatially and numerically challenged.

I left the bubble on Jan 2 and made my way out to 6666:66:6666 for the start of my trip to the core. I then ran what I'm calling Route 66 all the way in to 6666:66:25900 in a (pretty) straight line. I don't think I wandered more than a few light years off the route.
Then I turned sharp left and followed the X:66:25900 line in to straight above Sag A, and then a couple of jumps down and I was HERE!
Route 66! A road to the core for the spatially and numerically challenged.