A very simple belt anchoring system centered around a belt clip design I originally came across by Area51.
I've include clips for both the standard ANET-A8 belt that comes with the kit and another which fit standard GT2 belts.
In version 2 of the clips, I've expanded on the original design by adding a slot to hold a little extra length of belt in the case that you need to make it a bit longer in the future.
I've also included some extremely simple X and Y Carriage mounts for the ANET-A8. The the Y anchor was designed for a belt attachment point which is ~12mm lower than the base of the carriage (with the 'H' crossbar on top).
The spacer is there in case you need the belt attachment point a little lower.
BTW: If you use the X/Y Anchors, use a couple of M3 washers to prevent your belt from slipping off.