I noticed that the Octave Forge 'Statistics' package currently doesn't have Matlab's bootci function for calculating bootstrap confidence intervals. I wrote a bootstrap confidence interval function compatible with Octave/Matlab called ibootci.m, which is available on GitHub
From a user perspective it has much the same syntax as Matlab's bootci function but has extended capabilities (double bootstrap) and functionality (some support for complicated dependence structures). I can provide this for the statistics package along with a wrapper function called bootci that includes the option to calculate BCa intervals has features strictly only available in Matlab's bootci.
Interested? This is my first time interacting with this mailing list so I'm not that familiar with the process of contributing.
The best way is to post the files contributed to the patch tracker . Try to follow the programming  and documentation  syntax conventions we like to use. However, people can fix that for you, so don't worry too much about it initially. It's also important to include unit tests  so that users can verify that your program works as intended.