Contrary to what's published in the documentation and install notes on Macports, I've come to the conclusion that, if you're using OS X 10.4, you'll need to update to the xcode version on the Apple Developer Connection anyway, so I'm not sure I see the point finding the original OS X install CDs/DVDs.
I haven't tried it that way, but I went through a frustrating process before.
Oddly enough, I read another official install guide on the Macports site that suggested the same (i.e. go straight to ADC). Sorry, but I can't find it to reference right now.