If you want the trigger level for Local Save, it's in localsave.xml.

If you want the trigger level for FTP Upload, it's in ftp.xml.

Every camera has its own localsave.xml, ftp.xml, cam.xml, etc. If you work your way down the directory tree starting at:
Documents and Settings\Application Data\Seiz System Engineering\AbelCam\
you'll see a directory for each of your cameras. The .xml files are in those directories.

Changing settings externally on the fly like that could get tricky, as I'm not sure what exactly would tell AbelCam that it needs to re-read the xml file. Maybe SSE can answer that part, 'cause I don't know.

EDITED to add: I just realized you are the same guy I was talking to about changing driver settings on the fly, and you were going to use NET STOP and NET START to pull it off. If you run AbelCam as a servlce that tactic should take care of getting it to read the new motion trigger too.

Let us know how it turns out; both the driver settings and the motion trigger. This topic comes up from time to time and since I never seem to have time to try it myself, it would be cool if you would post what worked for you we can all read about it.