Source codes are available for the following versions:
You can also download the latest source using subversion. Locate32 subversion repository is available on the address http://svn.locate32.net/locate32/. This repository is public so that anyone can view the files in the repository. An introduction to download sources from the repository and combile sources is here. For a Windows subversion client, check for example Tortoise SVN.
If you are interested of developing Locate32, please contact the author to get an account to the repository with writing permissions.