Makefile for dummies? Mac OS X

I am having trouble understanding an answer to a previous question I asked here on stackoverflow located at:

More efficient R / Sweave / TeXShop work-flow?

The answer in particular is from user: las3rjock who suggests creating a "makefile" and running the makefile to automate compilation of a .Rnw in R (Sweave) and then in LaTeX. I don't know what a makefile is, or how to use it in Terminal (?) on Mac OS X. My internet searching has returned things above my knowledge level. I guess I need some hand holding to create and run a makefile.

Could anyone give "dummy" instructions on how to create a makefile to run Sweave / LaTeX, or more to the point, utilize the answer from las3rjock in the previous question? Thank you!

I wrote a post with links on getting started with makefiles for Sweave.

From the post:

• Ross Ihaka has a quick introduction to makefiles focusing on Sweave, R, and LaTeX
• Charlie Gibbons wrote a document with LaTeX, Sweave, and Beamer examples of makefiles
• Gregor Gorjanc shows an example Sweave make file using his custom Sweave command
• Documentation on GNU Make

I also posted four sample Sweave documents. Each one has full source code available on github. Each one uses a makefile. In the first two tutorials, details of the makefile are described:

• Sweave Tutorial 1
• Sweave Tutorial 2
• Sweave Tutorial 3
• GitHub Repository of what will be Sweave Tutorial 4