Here is an interesting post from the old IFI Robotics forum that describes what is going on "under the hood" of a Victor.
http://www.ifirobotics.com/forum/viewtopic.php?t=317
Note that there are only 94 discrete output states in each direction. This would make a look-up table a pretty attractive solution. Also, "Be aware that it may take 3 or 4 input steps before the Victor changes its Output."
EDIT: Although this post seems to contradict the last bit about latency:
http://www.ifirobotics.com/forum/viewtopic.php?t=375