The Developer Installation Guide is a good place to start for those wishing to customise/enhance ReDBox or Mint.
Our developer (technical) mailing list is a great first stop to see if others are sharing your issues: http://groups.google.com/group/redbox-dev
Additionally, The Fascinator (the underlying platform) has code available at:
If you haven't used Git before, check out Pro Git for a handy reference.
We had previously (prior to Sept 2012) managed the code in GoogleCode:
The various issues and documentation are being migrated throughout Sept & Oct 2012.
ReDBox and Mint utilise Apache Maven for build management. It's a very comprehensive system - if you've never been involved with Maven, it's best to check out Maven: The Complete Reference hosted by Sonatype.
The development server (http://dev.redboxresearchdata.com.au/) hosts a number of development-related systems, including a maven repository and continuous integration (CI) server. The CI jobs also generally produce JavaDoc - this can be handy.
As ReDBox and Mint are based on The Fascinator platform, it's worth heading over to that site for further technical documentation: http://sites.google.com/site/fascinatorhome/