Xcode is required, use the standard 3.2.6 release.
After installing Xcode proceed with the following:
1. Install darwin-xtools (these provide assembler, linker and a few other essential tools).
2. Install Apple make.
3. Download bsdtar and replace its binary in `/usr/bin` (this is a temporary measure to fix a minor defect in the OS image).
Once these steps are done, bootstrap curl and PPCPorts can be installed.
Finally, if you want to use X11/GTK-based apps, wipe out archaic X11 implementations from Apple or XQuartz:
$ sudo rm -rf /usr/X11* /System/Library/Launch*/org.x.* /Applications/Utilities/X11.app /etc/*paths.d/X11
$ sudo pkgutil --forget com.apple.pkg.X11User
$ sudo pkgutil --forget org.x.X11
See more here.
P. S. Assuming you will largely use pre-built packages, this should suffice. For a fully-functional development environment several other binaries should be replaced or rebuilt (m4, bison etc.). You will also likely need to replace the same binaries in `/Developer/usr/bin`, since some ports will pull them from there.