Tex for producing packages (and whatever else)
All you needed was the FAQ: http://cran.r-project.org/bin/macosx/RMacOSX-FAQ.html#TeX-suite-of-tools-for-documentation-_0028optional_0029 Simon and Stefano must find it frustrating to document all this and see it asked here so often.
The problem is that no-one asking a question knows the frequency at which is it asked! Hadley