In App-V 4, this was an app launch time script, which would make it a startvirtualenvironment script. If it only needs to run once, it would be better as a publish script.
The location choice depends on how you deploy the package. Global deployment (aka assigning to a group of machine names rather than user names) scripts go in the deploymentconfig file, and in the Machine Scripts section. Non-global deployments
usually go in the User Scripts section of the deploymentconfig file, but may go in the userconfig file (when used) also.
App-V 5 will break up the scriptbody into a Path (the exe part) and Arguments (the rest). The path must be a full path to the exe, without quotation marks or leading/trailing white space.
Tim Mangan MVP for App-V and Citrix CTP Author of AppV books: "The Client Book" and "OSD Reference Book" (http://www.tmurgent.com/Books )