Within an OSX package, how can I cleanup if an error occurs?

Within an OSX package, how can I cleanup if an error occurs?

I've built application that's distributed as a flat package on OSX. It
contains both preinstall and postinstall scripts, as well as a couple of
plugins that provide custom UI. And everything seems to work just
fine....except when it doesn't. :-)
If an error occurs for any reason during install (disk space, permission
issues, etc.), there doesn't seem to be a mechanism to allow my package to
react. In those cases, I'd really like to launch a script to clean up
temporary files and remove the partially installed app altogether.
Does anyone know of a way to accomplish this? Or am I asking too much from
a package based install?
Thanks in advance!