I personally use MainMenu from MacUpdate as it resides in my menu bar and I can assign quick batch tasks to it as well as perform a lot of other useful features. MainMenu -> Finder -> Show Invisibles. Comes in very handy to have it be that quick. Of course there are other ways to show hidden files but this is just preference.

Also, for navigating the to Installation folder of the Install DVD you could just launch a Finder window then use the Go menu: Go -> Go To Folder (or [shift]+[apple/cmd]+[G]) then type in:
/Volumes/iPC 10.5.6 Mac OS X Install DVD/System/Installation/Packages/

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