Hi
The alternative to David's suggestion is to use PACIFIST (shareware, search versiontracker.com) to extract & install DVD Player.app, then use
DVD Player patch to allow it to work with an external DVD drive (by default DVD Player only runs on an external if an internal DVD drive is present).
Pacifist for Panther DVD PLayer.app directions:
1)With the OS Install disc 1 in your mac, open Pacifist.
2)Select "Open Mac OS X Install Packages" and Pacifist will load the packages folder on the discs (you'll have to feed it all three discs).
3)Select the arrowhead "Contents of EssentialSystemSoftware.mpkg"
4)select the arrowhead "Contents of Essentials.mpkg"
5) Select the arrowhead in front of the Applications folder
6)Select "DVD Player.app"
7)Select "Install" from Pacifist menu
8)Enter your password at the prompt
you're good to go.
Tiger may not be indentical, I've not tried it.