StatsReader v2.1 HowTo:

New in 2.0: if setting target size to "0" you can use StatsReader
to add keyframes in desired locations. Make sure to use a different
filename for the target file and set that file up in xvid as first
pass statsfile. Since the frametypes are gathered from the first
pass file, setting them only in a 2nd pass file won't work.
[Note that you need a special XviD dev-api-3 build for this when
using bframes (with suxendrol's controlled mode), without bframes
or in the stable build this should work out of the box.]

New in 2.0a: merging stats files. If you somehow accidently abort
a first pass and simply want to continue, you can now do a 2nd first
pass (using another name for the target stats of course) and
start at the next frame to the last frame from the first file.
When you're done, simply open the first file as usual, then hit
"merge". Open the 2nd file. Then another dialog pops up asking
for a new target stats-file, choose a new name.
This isn't perfect as on that cut the bitrate will go nuts for a
second, but it produces still a valid output.
I found it to be useful ;-)

New in 2.1:
Statsreader can now read dev-api-4 sats-files. There is no support for
external scaling anymore in dev-api-4, so there's no need for all the
functions of StatsReader for these xvid versions. It still helps
getting some insights into the first pass though.
Still missing: support to write dev-api-4-statsfiles for the "add
keyframe" feature.