Is it possible to use ET GeoWizard or XTools Pro tools in automation of mapping in either in ModelBuilder or Python?
Yes, I believe it is possible to use both in Python scripts. XTools has some samples in your install directory (mine is an older version and is installed at C:\Program Files (x86)\DataEast\XToolsPro 7.1\Scripts). You need to import the Toolbox. Here is an example (assuming you are on ArcGIS 10 and using arcpy, otherwise use the geoprocessor):
It's been a while since I used ET Geowizards tools in a script, but here is how I'm betting that works (along the same lines as with XTools):