how to tell pkg-list not to deinstall/overwrite certain files

[Aryeh Friedman]

I am doing a lot of inter-machine testing of a private port (will be
released soon as a actual port) but need to tell "make deinstall" not to
delete a certain file... how do we do this?... background one thing we are
testing is the ability to upgrade the port (privately) and it must not nuke
our settings file on the test machines because the default config provided
by our port is inappropriate for how we have things configured (it is
correct for 99.9% of everyone else though).

Namely we need:

1. Do not delete  /usr/local/etc/petitecloud/settings on deinstall
2. Do not overwrite it with a new version on install (if present else
install it)