1. The easy way
   
   Type the following command line in R
  
   > source("http://www.math.ntnu.no/inla/givemeINLA.R")

   later on, you can upgrade using

   > inla.upgrade()

(Ooops: There are two versions of the R-INLA package; one more stable and one that is in active development. To get the test-version do

  > inla.upgrade(testing=TRUE)

but you can go back to the more stable version with testing=FALSE. See this link for further information.)

2. The regular way:

Download the package choosing one of the following alternatives 


   and install it. For Linux and Mac, do
 
   > install.packages("INLA.tgz", repos=NULL, type="source")

  for Windows, start R and select the Packages menu, then Install
  package from local zip file by find and highlight the location of the
  zip file and click on open.

Small prints:

• All source code for this project is now hosted by google code and you can view the latest changes here.
  
• Software licenses
  
• In case you want to know the details the inla-program which is the backend-program which do all the computations, you can download the manual here. However, it is not up-to-date with respect to new models but the input/output file-format is well described. 
• Compile it yourself? Download build-packages and compile it yourself. You will need to install mercurial which is available in all larger Linux distros and binaries for Mac OSX is available from the same site.