The file has to be in the temporary folder to execute before an update.
Execute File Before Update
mrowleyHow do I execute a file before an update?This documentation shows options that dont exist in my 2.6.18.4 interface?http://wyday.com/wybuild/help/executing-files.php
FYI: Also your stop a service before install "Update Action" fails to install the update if a service doesn't exist, who test this stuff before release and then doesn't include an option for this possibility.