The standard install.sh, uninstall.sh and update.sh, as defined in the src/paks/default directory, are as follows (I deleted a bit of comments):

filename=default_install.sh

#!/bin/bash
. /opt/pakfire/lib/functions.sh
extract_files
restore_backup ${NAME}
start_service --background ${NAME}

filename = default_uninstall.sh

#!/bin/bash
. /opt/pakfire/lib/functions.sh
stop_service ${NAME}
make_backup ${NAME}
remove_files

filename = default_update.sh

#!/bin/bash
. /opt/pakfire/lib/functions.sh
./uninstall.sh
./install.sh

My plugin does not provide a daemon, it provides drivers for the cups daemon instead, so I don't need to start/stop anything, I should restart the cups daemon instead, so I modified the above files as follows:

filename = install.sh

#!/bin/bash
. /opt/pakfire/lib/functions.sh
extract_files
restore_backup ${NAME}
restart_service cups

filename = uninstall.sh

#!/bin/bash
. /opt/pakfire/lib/functions.sh
make_backup ${NAME}
remove_files
restart_service cups

update.sh remained untouched.