Xcode 3.2.5 has to be used as it is the latest xcode that allows Universal binary creation.
Xcode 3.2.5 can be downloaded from here:
https://developer.apple.com/downloads
Before building the Scintilla.framework (included in Scintilla download file), in the project properties, change the base SDK to 10.5, and
architectures to Standard (32/64- bit Universal). Scintilla is available from sourceforge: http://sourceforge.net/projects/scintilla/files/scintilla/
Xcode 3.2.6 does not support ppc.
You can download it, already built, from here:
http://code.google.com/p/fivemac/downloads/detail?name=Scintilla-framework_Universal.zip&can=2&q=