I tried modifying paths to 'zope instance home' in bin/runzope, bin/runzope.bat and etc/zope.conf.
Note that runzope.bat is only relevant on windows, and runzip is only relevant on unix/linux/OSX. If you're on *nix, you also need to modify bin/zopectl if you use it. Also check the paths to all the other defined variables. e.g. ZOPE_HOME, CONFIG_FILE, SOFTWARE_HOME, PYTHONPATH.
**Is the old zope instance home _path_ burned into a binary somewhere that cannot be changed??**
It should not be.
e.g. Does Data.fs depend on old path somehow??
There used to be problems with skin directories keeping old paths, but that may be fixed. See http://zopelabs.com/cookbook/1021216110 I have not had any such problems in a long time, but I'm not sure if that's because it's fixed or because I haven't tried to break it :) -PW