[Archmage]

What I use is botman's bsp tool. You print out the map's models and get something like below:

Model index : 1
Model boundbox min (X): -144.000000
(Y): -2112.000000
(Z): -1728.000000
Model boundbox max (X): -112.000000
(Y): -2104.000000
(Z): -1680.000000

To get the origin out of this you take each value of x, y and z and split the difference. So for x value you take -144 and -112 giving you an x value of -128.

It is still a bit tedious but this is the only way I know how to do it.