How to Edit PKG

Unpack .pkg

mkdir Foo
cd Foo
xar -xf ../Foo.pkg

$ xar -cf ../Foo-new.pkg *

$ mkdir Foo
$ cd Foo
$ xar -xf ../Foo.pkg
$ cd foo.pkg
$ cat Payload | gunzip -dc |cpio -i

edit Foo.app/*

$ rm Payload
$ find ./Foo.app | cpio -o | gzip -c > Payload
$ mkbom Foo.app Bom # or edit Bom

edit PackageInfo

$ rm -rf Foo.app
$ cd ..
$ xar -cf ../Foo-new.pkg