hi floppy,
as far as i know it's not possible to include in the dep-file something different than a tcz-package.
so a script in the dep-file won't be executed.
i would recommend you another approach:
prepare yourself a individual dummy-package f.e. mycups-pdf.tcz
this dummy-package has in it's dep-file the original dependency to cups-pdf, that means everything stays compatible even the cups-pdf.tcz will be updated in the future.
cups-pdf.tcz loads cups.tcz as a dependency.
in this dummy-package mycups-pdf.tcz you can include a script under /usr/local/tce.installed/ that starts cups,
and at the same time cups-pdf is loaded, too.
f.e. this could be /usr/local/tce.installed/mycups-pdf
#!/bin/sh
sleep 3
sudo /usr/local/etc/init.d/dbus start
sudo /usr/local/etc/init.d/cups start
now you can include mycups-pdf.tcz in the dep-file of minefield and everything should work as you expected.
i use this approach for sound and printing in some individual meta-packages all the time and it works stable.