The method of customizing the package in this original post has been deprecated. Refer instead to:
https://docs.jamf.com/jamf-connect/administrator-guide/Custom_Branding.html - Packaging custom branding assets
https://docs.jamf.com/technical-papers/jamf-pro/deploying-jamf-products/Jamf_Connect_Deployment.html - Knowledge base article on deploying all the Jamf products
And, if you would like to wrap the JamfConnect.pkg installer at the same time, refer to:
https://github.com/sean-rabbitt/JamfConnectMetaPackageSample

