Click to download the current official version (5.2; 28 August 2012; 7.7 MB) of CMLCA. Clicking means you accept the license conditions.
Click to download version 5.2beta (9 February 2014; 25 MB) of CMLCA.
Click to download version 5.1 (8 June 2010; 3.9 MB) of CMLCA.
Click to download version 4.2 (26 May 2004; 3.2 MB) of CMLCA.
See the page on getting CMLCA for a list of data (for purchase or for download), featuring names like ecoinvent and the US LCI database.
There is a page with a couple of example projects.