I've been trying to achieve this as well, since I have image cache among the assets and don't want to include it in the transport package. I've came across this solution and I've found out it works, but not the way I'd want it to. The xPDO transport passes the options only to the install and uninstall functions - this means the store function includes all files in the package. When the package is installed however, the install function receives the 'copy_exclude_patterns' directive and ignores these files.
